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Water bears will survive the end of the world as we know it.

Only one calamity could kill tardigrades — and chances of that happening are slim


LIFE GOES ON   They may look like microscopic caterpillars, but don’t let their quaint appearance fool you — water bears are no joke. These creatures, shown here in a 3-D rendered illustration, will probably soldier on long after humans are gone.


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By Maria Temming

July 14, 2017 at 11:40 am

Water bears may be Earth’s last animal standing.

These tough little buggers, also known as tardigrades, could keep calm and carry on until the sun boils Earth’s oceans away billions of years from now, according to a new study that examined water bears’ resistance to various astronomical disasters . This finding, published July 14 in Scientific Reports , suggests that complex life can be extremely difficult to destroy, which bodes well for anyone hoping Earthlings have cosmic company.

Most previous studies of apocalyptic astronomical events — like asteroid impacts, neighboring stars going supernova or insanely energetic explosions called gamma-ray bursts — focused on their threat to humankind. But researchers wanted to know what it would take to annihilate one of the world’s most resilient creatures, so they turned to tardigrades. 

The tardigrade is basically the poster child for extremophiles. These hardy, microscopic critters are up for anything. Decades without food or water? No problem. Temperatures plummeting to –272° Celsius or skyrocketing to 150°? Bring it on. Even the crushing pressure of deep seas, the vacuum of outer space and exposure to extreme radiation don’t bother water bears.

Water bears are so sturdy that they probably won’t succumb to nuclear war, global warming or any astronomical events that wreak havoc on Earth’s atmosphere — all of which could doom humans, says Harvard University astrophysicist Avi Loeb. To exterminate tardigrades, something would have to boil the oceans away (no more water means no more water bears). So Loeb and colleagues calculated just how big an asteroid, how strong a supernova, or how powerful a gamma-ray burst would have to be to inject that much energy into Earth’s oceans.

“They actually ran the numbers on everyone’s favorite natural doomsday weapons,” marvels Seth Shostak, an astronomer at the SETI Institute in Mountain View, Calif.

Loeb’s team found that there are only 19 asteroids in the solar system sufficiently massive enough to eradicate water bears, and none are on a collision course with Earth. A supernova — the explosion of a massive star after it burns through its fuel — would have to happen within 0.13 light-years of Earth, and the closest star big enough to go supernova is nearly 147 light-years away. And gamma-ray bursts — thought to result from especially powerful supernovas or stellar collisions — are so rare that the researchers calculated that, over a billion years, there’s only about a 1 in 3 billion chance of one killing off tardigrades.  

“Makes me wish I were an extremophile like a tardigrade,” says Edward Guinan, an astrophysicist at Villanova University in Pennsylvania who was not involved in the work.

But even tardigrades can’t cheat death forever. In the next seven billion years, the sun will swell into a red giant star, potentially engulfing Earth and surely sizzling away its water. But the fact that tardigrades are so resistant to other potential apocalypses in the interim implies that “life is tough, once it gets going,” Shostak says.

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A big discovery of a tiny critter

Juan Siliezar

Harvard Staff Writer

Water bear fossil found in 16-million-year-old amber is the third tardigrade species ever discovered

Good luck finding an animal tougher than a tardigrade.

These tiny creatures are famous for their ability to survive in the most extreme conditions, including boiling water, freezing water, and even the vacuum of space. Called water bears or moss piglets because of their appearance under a microscope, tardigrades are the smallest-known animals with legs. They have a pudgy body — no larger than a pencil point — their eight legs have several pointed claws at the end, and they have a spear-like sucker that extends from their mouth.

Tardigrades are found on all the continents (basically wherever there is water) and have survived on Earth for more than 500 million years. Despite such a long evolutionary history and global presence, the fossil record on tardigrades is thin, with only two clear examples identified as separate species ever found. But thanks to a 16-million-year-old piece of amber discovered in the Dominican Republic, scientists can now add a third — a discovery immortalized in word and song.

Magnified example of a tardigrade, with its pudgy body that is no larger than a pencil point.

Credit: Phil Barden/NJIT

The researchers from Harvard and the New Jersey Institute of Technology who made the discovery describe their finding in a new paper in the Proceedings of the Royal Society B. The ultra-rare fossil can help shed new light on these ancient animals and provide new evolutionary insight into how the 1,300 tardigrade species that exist today evolved.

The specimen is the first water bear fossil ever recovered from the Cenozoic era, which started 66 million years ago and encompasses the planet’s current geological era. The researchers believe this is the best-imaged tardigrade fossil to date. In fact, they were able to describe microscopic details on parts of the mouth and needle-like claws that are about 20 to 30 times finer than a human hair. They were also able to get an unprecedented look at the internal anatomy of its foregut, which played the key role in identifying the fossil as a new genus and species.

“We could see it had this unique foregut organization that warranted for us to formalize a new genus within this extant group of tardigrade superfamilies,” said Marc A. Mapalo, a Ph.D. candidate who does his work in the Department of Organismic and Evolutionary Biology, Harvard’s Graduate School of Arts and Sciences, and is lead author of the study. “We saw characters that are not observed in extant species, but are observed in the fossils. This helps us understand what changes in the body occurred across millions of years.”

The researchers were able to examine these distinct anatomical features with a confocal laser microscope, a piece of equipment that uses a laser instead of visible light to peer into the specimen and produce a high-quality image. Usually, it is used to see biological and molecular processes such as cell division.

“Using this high-powered technique that is usually employed for studying cell biology, it was possible to obtain extremely detailed anatomical information,” said Javier Ortega-Hernández, an assistant professor in OEB and curator of invertebrate paleontology in the Museum of Comparative Zoology. “We saw the whole animal in way better detail than previously possible using conventional light microscopy.”

The researchers called the new species Paradoryphoribius chronocaribbeus . The name uses the Greek word for time, “chrono,” and refers to the Caribbean region where it was found, “caribbeus.” The new species is a relative of the modern living family of tardigrades known as Isohypsibioidea .

The other two fully described unequivocal tardigrade fossils are Milnesium swolenskyi and Beorn leggi , both known from Cretaceous-age amber in North America. This makes the new Dominican species the first water bear fossil to be found outside that region.

Co-author Phillip Barden from the New Jersey Institute of Technology introduced the fossil to Ortega-Hernández and Mapalo in 2019 after visiting the Museum of Comparative Zoology as a guest speaker. Mapalo, who was new to the lab, is a specialist in tardigrades and took the lead in analyzing the fossil using confocal microscopes in the Harvard Center for Biological Imaging.

Mapalo and Ortega-Hernández hope their success with the confocal microscope will inspire other researchers to use it to examine their own amber samples. The pair will also continue to employ the technology to study other tardigrades fossils trapped in amber.

Meanwhile, Mapalo has written a song (as one does) to celebrate number three.

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Microscopic water bears, also known as tardigrades

Tiny animals survive exposure to space

Scientists recently revealed that tiny creatures called water bears are the first animals to survive exposure to space. Sending water bears into space is one of several ESA experiments looking at organisms which can survive longer periods in open space.

Water bears, also known as tardigrades, are very small, segmented animals. The largest species is just over one millimetre in length. Water bears live in temporary ponds and droplets of water in soil and on moist plants. They are known to survive under conditions that would kill most organisms – they can withstand temperatures ranging from -272 deg C to +150 deg C, they can be without water for a period of 10 years, and they are extremely resistant to radiation.

Knowing them to be so hardy, the Swedish and German scientists behind the ‘Tardigrades in space’ (TARDIS) experiment wanted to find out how the water bears would fare in the harsh space environment. For 12 days in September 2007, some 3000 water bears hitched a ride into space on ESA’s orbital Foton-M3 mission.

The Foton-M3 capsule spent 12 days orbiting the Earth in September 2007

“Our principle finding is that the space vacuum, which entails extreme dehydration and cosmic radiation, were not a problem for water bears,” says TARDIS project leader Ingemar Jönsson, from the University of Kristianstad in Sweden.

That the water bears survived, shows just how robust they are. The next step will be to understand what mechanism makes this possible. Jönsson: “How do their cells stabilise the membrane and DNA when they dry out for example?” Understanding these mechanisms can open the door to many insights both in space bioscience and in other areas.

The tardigrades join a fairly select group of organisms which are able to cope with the extreme conditions in space. Over the past 10 years, other ESA experiments have shown that lettuce seeds and lichen were also able to survive exposure to space. If shaded from direct sunlight, bacterial spores are also known to survive for many years under space conditions.

Space exposure experiments are carried in Biopan on the outside of the Foton capsule

“The water bears are something new. Nobody knew about that capability” says René Demets, ESA project biologist. “The question is why are terrestrial organisms prepared to survive exposure to space conditions? Is there a rationale? Nobody knows at the moment.”

Survival in space is often linked to a much wider theory about how life originated here on Earth. “Perhaps the starting point for life was not even here on Earth,” says Demets. “Could life as we know it have started elsewhere, to be carried later for instance on a meteorite and delivered here on Earth? Favourable conditions meant that it could further propagate, develop, grow and live on. Now we have actually found some organisms that can survive under harsh space conditions.”

If these organisms were to travel on board a meteorite, they would also have to survive the entry through Earth’s atmosphere. ESA’s series of Stone experiments, also conducted on the Foton missions, show that in the upper layer of the meteorite, up to 2 cm depth, nothing could survive the atmospheric entry because of the high temperature and pressure. Only an organism that could live inside deeper cracks or pores in the rock could perhaps survive.

Expose hardware

These space exposure experiments have so far been limited to one or two weeks in mission duration. ESA is now also testing longer duration exposure with an suite of experiments on the International Space Station called Expose. Several trays filled with terrestrial organisms are already installed on the outside of the European Columbus laboratory as one of the nine payloads of the European Technology Exposure Facility (EuTEF). Another Expose unit, scheduled for launch on a Russian Progress cargo carrier in November, will be attached to the Russian segment of the Space Station.

“After about one and a half years we will get the Expose trays back and see what the situation is after long duration exposure,” explains Martin Zell, Head of ESA's ISS Utilisation Department. “We could have a brilliant result with survival of the organisms as we have seen with the water bears, or we could have a quite negative result and know for sure that long-duration exposure will never work. With these experiments we are probing the alterations of organisms in space and their ultimate limits of survival.”

For more information please contact:

Martin Zell ESA Head of ISS Utilisation Department Directorate of Human Spaceflight Martin.Zell[@]

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Temperature fluctuations in a simple, single-component organic fluid on Earth (left) and onboard Foton-M3 (right)

Fluid theory confirmed by Foton

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Why NASA Is Blasting Water Bears And Bobtail Squid Into Space

Joe Hernandez

research on water bears

Scientists will study whether microgravity has an impact on the relationship between newly hatched bobtail squid and their symbiotic bacterium. Jamie S. Foster/University of Florida hide caption

Scientists will study whether microgravity has an impact on the relationship between newly hatched bobtail squid and their symbiotic bacterium.

When SpaceX makes its 22nd resupply mission to the International Space Station on Thursday, it will be carrying two very special guest species: water bears and bobtail squid.

The animals are being launched into the cosmos in the name of science, as NASA researchers attempt to learn more about how the conditions of spaceflight can affect biological organisms and, by extension, future astronauts.

Water bears: basically indestructible

Tardigrades are microscopic organisms better known as "water bears" because of their shape and the fact that they commonly live in the water. (They have also been called, endearingly, "moss piglets.")

Water bears can survive in conditions that would prove fatal for most other animals, such as exposure to extreme temperatures, pressure, and radiation. The fact that they are basically indestructible, according to NASA, makes them the perfect test subjects for an experiment about the effects of spaceflight on biological survival.

research on water bears

Water bears are basically indestructible, making them, according to NASA, the perfect test subjects for an experiment about the effects of spaceflight on biological survival. Thomas Boothby/University of Wyoming hide caption

Scientists want to see how traveling through the solar system affects water bears because it might help them understand what happens to astronauts when they are rocketing through space. The agency may use that information to develop "countermeasures" to make future voyages easier on human travelers.

NASA Picks Twin Missions To Visit Venus, Earth's 'Evil Twin'

NASA Picks Twin Missions To Visit Venus, Earth's 'Evil Twin'

"Spaceflight can be a really challenging environment for organisms, including humans, who have evolved to the conditions on Earth," said principal investigator Thomas Boothby.

"One of the things we are really keen to do is understand how tardigrades are surviving and reproducing in these environments and whether we can learn anything about the tricks that they are using and adapt them to safeguard astronauts."

The friendly microbe of a bobtail squid

Thousands of microbes live inside the human body and work to keep us healthy.

But scientists don't have a clear picture of how microgravity — which allows the kind of floating weightlessness experienced by astronauts when they travel into space — affects those microbes.

That is the subject of an ongoing NASA research program called the Understanding of Microgravity on Animal-Microbe Interactions, or UMAMI.

"Animals, including humans, rely on our microbes to maintain a healthy digestive and immune system," says UMAMI principal investigator Jamie Foster. "We do not fully understand how spaceflight alters these beneficial interactions."

That's where the bobtail squid come in.

Scientists will study whether microgravity has an impact on the relationship between newly hatched bobtail squid, or Euprymna scolopes , and their symbiotic bacterium, Vibrio fischeri .

The goal is to use what they learn about the relationship between squid and the microbes to help better prepare astronauts for lengthy space missions and preserve their health while they're out there.

The experiment could also lead to a new understanding of the ways animals and helpful microbes interact and may even have applications for improving health on Earth, NASA said.

How One Of The World's Toughest Creatures Can Bring Itself Back To Life

The Two-Way

How one of the world's toughest creatures can bring itself back to life.


How tardigrades bear dehydration

A new mechanism explains how water bears survive in some extreme conditions.

Some species of tardigrades, or water bears as the tiny aquatic creatures are also known, can survive in different environments often hostile or even fatal to most forms of life. For the first time, researchers describe a new mechanism that explains how some tardigrades can endure extreme dehydration without dying. They explored proteins that form a gel during cellular dehydration. This gel stiffens to support and protect the cells from mechanical stress that would otherwise kill them. These proteins have also been shown to work in insect cells and even show limited functionality in human cultured cells.

Tardigrades often draw attention to themselves, despite being so tiny. Their uncanny ability to survive in situations that would kill most organisms has captured the public’s imagination. One could easily imagine that by decoding their secrets, we could apply the knowledge to ourselves to make humans more resilient to extreme temperatures, pressures, and even dehydration. This is just science fiction for now, but nevertheless, researchers, also captivated by the microscopic creatures, seek to understand the mechanisms responsible for their robustness, as this could bring other benefits too.

“Although water is essential to all life we know of, some tardigrades can live without it potentially for decades. The trick is in how their cells deal with this stress during the process of dehydration,” said Associate Professor Takekazu Kunieda from the University of Tokyo’s Department of Biological Sciences. “It’s thought that as water leaves a cell, some kind of protein must help the cell maintain physical strength to avoid collapsing in on itself. After testing several different kinds, we have found that cytoplasmic-abundant heat soluble (CAHS) proteins, unique to tardigrades, are responsible for protecting their cells against dehydration.”

Recent research into CAHS proteins reveals that they can sense when the cell encapsulating them becomes dehydrated, and that’s when they kick into action. CAHS proteins form gel-like filaments as they dry out. These form networks that support the shape of the cell as it loses its water. The process is reversible, so as the tardigrade cells become rehydrated, the filaments recede at a rate that doesn’t cause undue stress on the cell. Interestingly though, the proteins exhibited the same kind of action even when isolated from tardigrade cells.

“Trying to see how CAHS proteins behaved in insect and human cells presented some interesting challenges,” said lead author Akihiro Tanaka, a graduate student in the lab. “For one thing, in order to visualize the proteins, we needed to stain them so they show up under our microscopes. However, the typical staining method requires solutions containing water, which obviously confounds any experiment where water concentration is a factor one seeks to control for. So we turned to a methanol-based solution to get around this problem.”

Research on mechanisms related to dry preservation of cells or organisms could have many future applications. Kunieda and his team hope that through this new knowledge, researchers might find ways to improve the preservation of cell materials and biomolecules in a dry state. This could extend the shelf life of materials used for research, medicines with short expiry dates, or maybe even whole organs needed for transplants.

“Everything about tardigrades is fascinating. The extreme range of environments some species can survive leads us to explore never-before-seen mechanisms and structures. For a biologist, this field is a gold mine,” said Kunieda. “I’ll never forget New Year’s Day 2019, when I received an email from Tomomi Nakano, another author of the paper. She had been working late trying to see the condensation of CAHS proteins and observed the first CAHS filament networks in human cultured cells. I was astonished at seeing such clearly defined microscopic images of these. It was the first time I had seen such a thing. It was a very happy new year indeed!”

Knowing how to isolate and activate these special proteins, though, is just the beginning. Kunieda and his team plan to sift through more than 300 other kinds of proteins, some of which likely play a role in the incredible life-preserving ability of these tiny water bears.

  • Cell Biology
  • Molecular Biology
  • Biotechnology
  • Extreme Survival
  • Developmental Biology
  • Biotechnology and Bioengineering
  • Dehydration
  • Heat shock protein
  • Natural killer cell
  • Algal bloom
  • Human biology

Story Source:

Materials provided by University of Tokyo . Note: Content may be edited for style and length.

Journal Reference :

  • Akihiro Tanaka, Tomomi Nakano, Kento Watanabe, Kazutoshi Masuda, Gen Honda, Shuichi Kamata, Reitaro Yasui, Hiroko Kozuka-Hata, Chiho Watanabe, Takumi Chinen, Daiju Kitagawa, Satoshi Sawai, Masaaki Oyama, Miho Yanagisawa, Takekazu Kunieda. Stress-dependent cell stiffening by tardigrade tolerance proteins that reversibly form a filamentous network and gel . PLOS Biology , 2022 DOI: 10.1371/journal.pbio.3001780

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The Tardigrade: Practically Invisible, Indestructible ‘Water Bears’

research on water bears

By Cornelia Dean

  • Sept. 7, 2015

When scientists at the American Museum of Natural History mounted an exhibit about creatures that survive under conditions few others can tolerate, they did not have to go far to find the show’s mascot.

“We just got them from Central Park,” said Mark Siddall , a curator of the show, Life at the Limits . “Scoop up some moss, and you’ll find them.”

He was talking about tardigrades , tiny creatures that live just about everywhere: in moss and lichens, but also in bubbling hot springs, Antarctic ice, deep-sea trenches and Himalayan mountaintops. They have even survived the extreme cold and radiation of outer space.

Typically taupe-ish and somewhat translucent, and a sixteenth of an inch or so long, they are variously described as resembling minuscule hippopotamuses (if hippos had giant snouts and eight legs, each with several claws), mites or, most commonly, bears. Many people call them “water bears” or “bears of the moss.” (The word “tardigrade” is from the Latin for “slow walker” and pronounced TAR-dee-grade.)

Once an object of interest only among zoological specialists, tardigrades now are generating widespread enthusiasm. Admirers have produced artwork and children’s books about them, and have even organized the International Society of Tardigrade Hunters “to advance the study of tardigrade (water bear) biology while engaging and collaborating with the public.”

According to the society, formed this year at the University of North Carolina at Chapel Hill, people can find tardigrades if they gather some lichen or moss, especially on a damp day, put it in a shallow dish of water, and “agitate” it a bit. Debris will settle to the bottom of the dish, and tardigrades will probably be prowling in it.

The museum exhibit , which runs until January, also includes beetles, flowers, corals and other animals with unusual ways of coping with hostile environments. But its entrance is guarded by a 10-foot replica of a tardigrade, seemingly floating overhead. That’s fitting, because the tardigrade, which has a natural life span of about a year, is particularly impressive among the exhibit’s “extremeophiles.”

Confronted with drying, rapid temperature changes, changes in water salinity or other problems, tardigrades can curtail their metabolism to 0.01 percent of normal, entering a kind of suspended animation in which they lose “the vast, vast, vast majority of their body water,” Dr. Siddall said. They curl up into something called a “tun.”

Tuns can be subjected to atmospheric pressure 600 times that of the surface of Earth, and they will bounce right back. They can be chilled to more than 300 degrees Fahrenheit below zero for more than a year, no problem. The European Space Agency once sent tuns into space: Two-thirds survived simultaneous exposure to solar radiation and the vacuum of space.

Without water, “the damaging effects of freezing cannot happen,” Dr. Siddall explained. “It protects against heat because the water inside cannot turn into a gas that expands.” Even radiation needs water to do damage, he said. When cosmic radiation hits water in a cell, it produces a highly reactive form of oxygen that damages cell DNA. The tun doesn’t have this problem.

Tuns have been reconstituted after more than a century and brought back to life as tardigrades, looking not a day older.

Little is known about their evolution, which is too bad because biologists think it must have been interesting. But tardigrade fossils are hard to spot.

For a long time, biologists grouped them with arthropods, other creatures, mostly small, with eight legs. Only recently have tardigrades been given their own phylum, a major taxonomic category.

People who have become transfixed by tardigrades often say they came across a photo or article by chance.

“I just stumbled across it,” said Thomas Gieseke, an artist and illustrator in Merriam, Kan., who created “ The Tardigrade Queen ,” an acrylic-on-canvas work depicting a tardigrade on a throne, complete with tiara and royal crest, which was shown at the Todd Weiner Gallery in Kansas City, Mo.

“I stumbled on a photograph of one,” he said in a telephone interview. “I was just fascinated.” Though he has never seen a tardigrade in the wild, he said, “it’s just the most resilient creature on the face of the planet.”

“I like their little claws. They look like hands,” he added. “I thought, ‘This thing warrants royalty status.’ ”

Another tardigrade enthusiast, Michael W. Shaw of Richmond, Va., got interested in them more than a decade ago when he was helping his two daughters with school science projects. Though he knew nothing about tardigrades — his degree was in fine arts — he ended up taking microscopes into his daughters’ classes to spread the word about the fascinating creatures.

Later, he made his own contribution to the scientific literature. “I read a paper about tardigrades showing where they were in the U.S., and New Jersey, where we were living at the time, had a zero,” he said.

Mr. Shaw, who was living then in Somerset, decided to visit every one of the 21 counties in New Jersey and sample lichen and tree bark, two microenvironments hospitable to tardigrades. Between 2001 and 2009, he said, “I went to rural and urban sites, parking lots, nature preserves, anywhere. I found them in every county.”

His family thought his obsession was “strange,” he said, but the work, which he completed with the help of Dr. William Miller , a tardigrade expert at Baker University in Kansas, was published in The Journal of the New York Microscopical Society .

Then Vice did a video about Mr. Shaw. Soon new fans were arguing online about whether tardigrades came from outer space (an idea Mr. Shaw does not rule out) and how — or even if — they evolved.

Eventually, the work turned into two books Mr. Shaw has self-published — “Tardigrade Quiz and Fact Book” (Fresh Squeezed Publishing, 2014) and “Tardigrade Science Project Book” (Fresh Squeezed Publishing, 2011). Both discuss tardigrades and explain how young naturalists can gather specimens, make slides and otherwise dive into their snouty, eight-legged world.

Today Mr. Shaw’s tardigrade guides are selling slowly but steadily (typical reader comment: “Love those tardigrades!”), and he has done another guide for microscope hobbyists.

“The good news is you can find them almost anywhere,” according to the Tardigrade Hunters website. The group invites tardigrade hunters to submit their “prized specimens” for examination under the university’s high-powered microscopes.

The samples will not be returned, the society notes, but photographs of particularly interesting specimens may be posted online as the Tardigrade of the Week .

In ordinary life, tardigrades don’t get up to much. Dr. Siddall said that like most animals, they spend their time “hanging out and eating” plants and animals smaller than themselves, and possibly even indulging in cannibalism.

“People often say, ‘What’s their purpose? What’s their role in the universe?’ ” Dr. Siddall said. He has no ready answer. They might be useful for the study of suspended animation. But, he added, “are we going to find a way to put humans into suspended animation? I doubt it.”

Anyway, he said, attributing some kind of larger purpose to the tardigrade is not something a biologist would want to do. Creatures don’t have to have a purpose. “They merely are.”

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Tardigrades in Space Research - Past and Future

Erdmann weronika.

Faculty of Biology, Department of Animal Taxonomy and Ecology, Adam Mickiewicz University in Poznań, Umultowska 89, 61-614 Poznań, Poland

Kaczmarek Łukasz

To survive exposure to space conditions, organisms should have certain characteristics including a high tolerance for freezing, radiation and desiccation. The organisms with the best chance for survival under such conditions are extremophiles, like some species of Bacteria and Archea, Rotifera, several species of Nematoda, some of the arthropods and Tardigrada (water bears). There is no denying that tardigrades are one of the toughest animals on our planet and are the most unique in the extremophiles group. Tardigrada are very small animals (50 to 2,100 μm in length), and they inhabit great number of Earth environments. Ever since it was proven that tardigrades have high resistance to the different kinds of stress factors associated with cosmic journeys, combined with their relatively complex structure and their relative ease of observation, they have become a perfect model organism for space research. This taxon is now the focus of astrobiologists from around the world. Therefore, this paper presents a short review of the space research performed on tardigrades as well as some considerations for further studies.

What are Tardigrades?

Water bears (Tardigrada), discovered in 1773, are a phylum of small invertebrates belonging to the supertype Articulata. They can be found all over the Earth and can inhabit very diverse environments (from the deepest oceans to mountain tops). Water bears are small, cylindrical invertebrates, up to 2.1 mm in length, and are divided into five segments. The first segment contains the head and the next four each have one pair of unsegmented legs ending (most often) in claws. The tardigrade body is covered with a flexible cuticle, which is smooth or covered with gibbosities, spines or plates. Despite being so small, they have a very complicated internal structure. Water bears have a complete digestive system adapted, depending on the species, to consume algae, bacteria, fungal cells or small invertebrates such as rotifers, nematodes and other tardigrades. They have a well developed nervous system consisting of rings around mouth (brain) and an abdominal chain with segmental ganglia. They also have various sensory organs like papilla, chemoreceptors and eyes. Water bears can be dioecious and bisexual; in the second case, sexual dimorphism is sometimes present (especially in Heterotardigrada). In many species, the phenomenon of parthenogenesis is also present. Fertilisation can be external or internal. The eggs are covered with an additional shell, the smooth or ornamented chorion, and are laid freely (directly into the environment) or in old exuviae. After hatching, tardigrades moult between two to seven times. The young resemble the adults, and they reach sexual maturity after the second or third moult, which takes several days. Adult tardigrades live approximately two to several months (Nelson et al. 2015 ). Currently, approximately 1,200 tardigrade species are known (Degma et al. 2009–2016 ; Vicente and Bertolani 2013 ), although it is estimated that the real number of species is much higher. At present, this phylum is divided into two classes, Eutardigrada and Heterotardigrada. Eutardigrada consists mainly of freshwater and terrestrial species (marine species are extremely rare). The body of eutardigrades is translucent or milky white (but sometimes has different colouration) and is covered with a flexible cuticle and devoid of plates. Among Heterotardigrada, both marine and terrestrial species are present. Their body is covered with a cuticle that produces various kinds of plates (Nelson 2002 ; Nelson et al. 2015 ).

What Makes Them so Special?

As mentioned above, tardigrades live not only in freshwater and marine environments but also in terrestrial habitats. Terrestrial species can be found in mosses, lichens and soil where they are threatened by drying. In this situation, terrestrial species need a thin water film around their bodies in order to stay active. These species have also developed a special skill that protects them against the effects of dehydration: the ability to enter into a cryptobiotic state. There are several types of cryptobiosis: a) anoxybiosis, a reaction to lack of sufficient oxygen, b) cryobiosis, a reaction to freezing temperatures, c) osmobiosis, a reaction to excessive salinity, and the best known type of cryptobiosis, d) anhydrobiosis, a reaction to a lack of liquid water in the environment (Kinchin 2008 ). In the anhydrobiotic state, the metabolic activity of tardigrades drops to a very low level (Pigoń and Węglarska 1955 ). This latent state can occur at the egg stage as well as in adults and can be repeated multiple times (Kinchin 2008 ). Anhydrobiosis gives tardigrades resistance to a lack of water, but also to a number of physical factors such as high temperature, radiation or different kinds of chemicals, such as ethanol, hydrogen sulphide and carbon dioxide (Kinchin 1994 ; Ramlov and Westh 2001 ; Wełnicz et al. 2011 ; Guidetti et al. 2012 ). Not all Tardigrada species show equal resistance to drying out, as there are differences in drying tolerance even between populations of the same species (Jönsson et al. 2001 ; Horikawa and Higashi 2004 ). The entrance into anhydrobiosis is preceded by a preliminary phase, during which the tardigrade body undergoes a series of metabolic and anatomical changes that are necessary to survive the unfavourable conditions. The changes are easiest to observe as a shrinkage of the body (forming numerous folds which reduce the body’s surface area), namely the adoption of the tun formation (Baumann 1922 ). The tun form reduces the surface for evaporation and thus slows down the loss of liquid water (transpiration is reduced by about 50 %) (Wright 1989 ). The tun state also prevents the destruction of the internal and external organs during the drying process (Crowe 1975 ). When all free water evaporates from the tardigrade body, it begins the process of replacing the water bound to macromolecules. The lost water is replaced with bioprotectants such as trehalose, which protects macromolecules, such as nucleic acids and proteins, from losing their proper structure (Kinchin 2008 ). If the macromolecule structure is damaged, the cell dies. It is not certain how trehalose contributes to the protection of membrane proteins. It is also possible that the trehalose hydroxyl groups interact with hydrogen atoms replacing the same evaporating water (Kinchin 2008 ). In summary, trehalose is responsible for stabilising proteins, membrane lipids and nucleic acids (Webb 1964 ; Crowe 2002 ). However, it should be also emphasised that some tardigrades synthesise trehalose on a very low level (Wang et al. 2014 ). The other molecules involved in tardigrade cell protection during anhydrobiosis are LEA (late embryogenesis abundant), HSP (heat shock proteins), CAHS (cytoplasmic abundant heat soluble), SAHS (secretory abundant heat soluble) and aquaporin proteins (Förster et al. 2009 ; Yamaguchi et al. 2012 ; Grohme et al. 2013 ; Guidetti et al. 2011 , 2012 ; Wełnicz et al. 2011 ). The LEA proteins have similar functions to trehalose, but in addition to protecting the cell membranes and proteins, they can also act as a hydration buffer and sequester ions. They can also be responsible for cell structure protection through renaturation of unfolded proteins (Tunnacliffe and Wise 2007 ). In turn, the HSPs could work as molecular chaperons (Goyal et al. 2005 ) and participate in protein folding, and inhibiting protein aggregation. So far, it has been proven that this type of protein (presumably the Hsp70-90 proteins family) are produced and stored in organisms going into anhydrobiosis, but their role during desiccation is still uncertain (Ramlov and Westh 2001 ; Reuner et al. 2010 ; Wełnicz et al. 2011 ). The CAHS and SAHS proteins probably form a molecular shield in water-deficient conditions (Yamaguchi et al. 2012 ). Aquaporin proteins may play a minor role during anhydrobiosis by fine-tuning water transport and greatly increasing membrane permeability (Grohme et al. 2013 ). Also, possession of the ROS (Reactive oxygen species) scavenging enzymes could represent a crucial strategy to avoid damages during desiccation in anhydrobiotic tardigrades (Rizzo et al. 2010 ; Rebecchi 2013 ). However, most of the bioprotectants and mechanisms that protect tardigrade cells during cryptobiosis are still poorly understood or completely unknown.

Toughest Animals on Earth

The ability to enter into a state of anhydrobiosis (which distinguishes water bears from most other organisms) lets tardigrades resist many unfavourable environmental factors (Rebecchi et al. 2007 ). Moreover, tardigrades are able to survive in an inactive form for many years (from nine to 20 years in natural conditions) (Guidetti and Jönsson 2002 ; Rebecchi et al. 2006 ; Guidetti et al. 2012 ). Interestingly, the death of individuals that are in a long anhydrobiotic state is mostly caused by the drying process itself and not by the aging process. This phenomenon can be explained by the so-called “Sleeping Beauty” model, first reported in rotifers (Ricci 2001 ; Segers and Shiel 2005 ). At the time when the model was confirmed for rotifers, this kind of shift in the age of anhydrobiotic animal was also supposed for tardigrades (Hengherr et al. 2008 ). On the other hand, it was also proven that during anhydrobiosis, cell damages accumulate with time (Rebecchi et al. 2009a ). It is possible that such damages are accumulated in proportion to the time spent in anhydrobiosis and lead to animal death, even though desiccation itself does not seem to have an effect on tardigrade longevity and ageing (Guidetti et al. 2011 ). Water bears are also very resistant to extreme temperatures, and they can survive from −272.8 °C (Becquerel 1950 ) to about 150 °C (up to 15 min) (Rahm 1923 , 1924 , 1926 ). Resistance to low temperatures was investigated repeatedly during research on anhydrobiosis and on cryobiosis. One of the first studies showed that many different species of Tardigrada withstand immersion in liquid air ( ca. -190 °C), liquid nitrogen ( ca. -253 °C) and liquid helium ( ca. -272 °C) (Rahm 1923 , 1924 , 1926 ). Other studies demonstrated that some species inhabiting the Arctic soil can survive up to six years (74 months) at −80 °C (Newsham et al. 2006 ). These small invertebrates also exhibit significant resistance to low and high atmospheric pressures (from 200 to 280 hPa to 7,500 MPa) (Jönsson et al. 2008 ; Ono et al. 2008 ). Tardigrades in an anhydrobiotic state are also resistant to high doses of ionising radiation and X-rays ( ca. 5000 GY) (May et al. 1964 ; Horikawa et al. 2006 ). Some individuals are even able to survive very high doses of ultraviolet radiation (between 75 and 88 kJ m 2 ) (Altiero et al. 2011 ). Water bears are resistant to physical stressors as well as some chemical stressors such as hydrogen sulphide, carbon dioxide, ethanol (for ca. 10 min) and 1-hexanol (Baumann 1922 ; Ramlov and Westh 2001 ).

Unlike the other multicellular extremophiles, water bears are not only resistant in the anhydrobiotic state but also in the active state. Active tardigrades are able to survive in temperatures of about 38 °C (Li and Wang 2005 ; Rebecchi et al. 2009b ) and −196 °C (Ramlov and Westh 2001 ). They also exhibit a significant resistance to high atmospheric pressures (up to 100 MPa) (Seki and Toyoshima 1998 ). It is also known that tardigrades in the active state are almost as resistant to radiation as in anhydrobiosis (Jönsson et al. 2005 ; Horikawa et al. 2006 2009 ; Altiero et al. 2011 ).

Tardigrades in Space Research and Space Missions

All of the above mentioned features of tardigrades caused scientists to consider them in the context of space research. In 1964, in the article “Actions différentielles des rayons x et ultraviolets sur le tardigrade Macrobiotus areolatus ”, it was suggested for the first time that tardigrades, due to their enormous resistance to radiation, could be model animals for space research (May et al. 1964 ). Thirty-seven years later, in the article “Tardigrades as a potential model organism in space research”, Bertolani et al. ( 2001 ) suggested a similar concept. At the same time, studies focused on the phenomenon of cryptobiosis in tardigrades were conducted, revealing still greater resistance of this amazing animal to many unfavourable factors encountered in outer space. In 2007, Jönsson, based on knowledge resulting from these studies, showed that tardigrades can be suitable model organisms for astrobiological studies because of their ability to dehydrate, extreme temperature tolerance and radiation resistance (Jönsson 2007 ). Since that time, numerous articles suggesting that tardigrades can be used in space research have been published (Horikawa et al. 2008 ; Rebecchi et al 2010a ). The latest paper from early 2012 indicated that tardigrades are an excellent model for space research (Guidetti et al. 2012 ). While that paper emphasises the previously known extraordinary resistance of tardigrades, it also suggests that there is a greater complexity to tardigrade organisms. The authors repeatedly emphasise that the complex structure of tardigrades allows extrapolation of the results of such studies to vertebrates (including humans). In conjunction with their small body size, their relative ease to culture and obtain offspring further enhances their importance as a potential model species (Guidetti et al. 2012 ). In 2008, Horikawa et al. proposed Ramazzottius varieornatus Bertolani & Kinchin, 1993 as a model species in astrobiology research. In their paper they described a methodology for breeding this species under laboratory conditions. They also described the life history of this species and identified characteristics required to consider this particular species of tardigrade as a model (Horikawa et al. 2008 ). In the same year, it was also suggested that tardigrades could travel through space in a large meteorite and could probably confirm the theory of panspermia (Ono et al. 2008 ).

Based on researcher suggestions, a few space programmes focused on tardigrades were started and finished in recent years. In 2007, three projects were conducted during the FOTON-M3 mission studies. The Tardigrade Resistance to Space Effects (TARSE) Project was the first one involved in the mission of FOTON-M3. Its aim was to analyse the impact of environmental stress, life history traits and DNA damages in space (on board the spacecraft) on eutardigrade Paramacrobiotus richtersi (Murray, 1911). In this project active and anhydrobiotic tardigrades were exposed to radiation in microgravity conditions. Both active and inactive individuals had high survival rates with no induction of HSPs while showing an induction of the antioxidant response (Rebecchi et al. 2009c , 2010b , 2011a ). The next project involved in the mission of FOTON-M3 was TARDIS (Tardigrada In Space). The main goal of this project was to check whether tardigrades from two species, Milnesium tardigradum Doyère, 1840 and Richtersius coronifer (Richters, 1903), were able to survive conditions of open space. The experiments showed that tardigrades can survive exposure to the space vacuum, but the addition of factors such as ultraviolet solar radiation, ionising solar radiation and galactic cosmic radiation significantly reduced their survival rate (Jönsson, et al. 2008 ). In the third project from the FOTON-M3 mission, RoTaRad (Rotifers, Tardigrades and Radiation), scientists examined effects on initial survival, long-term survival and fecundity of selected species of limno-terrestrial tardigrades in extreme stress conditions (mainly cosmic radiation) (Persson et al. 2011 ). Next was the Endeavour mission in 2011 and the project TARDIKISS (Tardigrades in Space). The main aim of this project was to broaden our knowledge of life history traits and mechanisms of repairing structural DNA damage during exposure to space flight stresses (Rebecchi et al. 2011b ; Vukich et al. 2012 ). The first results showed that microgravity and cosmic radiation did not significantly affect the survival rate of tardigrades (Rebecchi et al. 2011b ; Vukich et al. 2012 ). However, Rizzo et al. ( 2015 ) showed a significant difference in activities of ROS scavenging enzymes, the total content of glutathione and the fatty acid composition between tardigrades sent into space and control animals on Earth. The last space research project involving tardigrades was the Phobos Life Project. It was a part of the Phobos Ground Mission. The goal of this project was to study how the living organisms survive during space flight conditions. Scientists wanted to test the viability of selected organisms during an interplanetary flight lasting approximately 34 months and verify the theory of panspermia (;wap2 ). For this mission, the same organisms already used in other space experiments, and well-known to be radiation resistant, were used. They represented all three domains of life (Bacteria, Eukaryotes and Archaea). A total of 10 different taxa were used (species or strains), including three species of tardigrades: M. tardigradum , R. coronifer and Echiniscus testudo (Doyère, 1840). Unfortunately, the experiments were not successful because the spacecraft carrying the whole apparatus crashed and burned over the South Pacific Ocean on January 15th 2012.

Further Perspectives

As demonstrated above, we already know quite a lot on the limits of endurance of tardigrades regarding various stress factors. However, we still do not know the exact mechanisms of action that protect and repair their bodies in unfavourable conditions. The understanding of these mechanisms and knowledge of the responsible genes is an important step in astrobiological studies, especially if it can be extrapolated to vertebrates (including humans).

There are many possible future directions of astrobiological research regarding tardigrades. For example, one experiment could evaluate the ability of tardigrades to survive in a simulated atmosphere of certain celestial bodies in our solar system (such experiments simulating Martian conditions were conducted on bacteria, cyanobacteria, lichens and also tardigrades (Cockell 2005 ; Johnson et al. 2011 ; Rebecchi et al 2010b ; Smith et al. 2009 ; Vera et al. 2010 ; 2014 ). This is interesting because a few of the celestial bodies in our solar system may periodically exhibit micro-environmental conditions appropriate for the survival of certain extremophiles. For example, it is well known that Martian soil contains water (Mitrofanov et al. 2014 ), and in some regions of Mars, in the summer periods, temperatures up to 20 °C were recorded (NASA, official webpage). Even if all environmental conditions are not entirely favourable for life, tardigrades are quite resistant in both the anhydrobiotic and the active state. Moreover, organisms which provide nourishment for tardigrades (e.g. bacteria, algae, rotifers or nematodes) are just as resistant as water bears (Guidetti and Jönsson 2002 ; Rettberg et al. 2002 ; Islam and Schulze-Makuch 2007 ; Meeßen et al. 2013 ). However, these relatively beneficial life periods are interrupted by periods of very unfavourable conditions for living organisms. This is where cryptobiosis has a potential and very important role. The ability to enter into cryptobiosis is helpful not only for travelling for long cosmic distances, but also for providing a possibility of surviving long periods when environmental conditions are unfavourable. This could enable researchers to determine whether tardigrades can survive and live on other planets in the solar system or on their moons. We should also continue studies on tardigrade resistance to combined stress conditions such as the combined effects of cosmic radiation and microgravity, or low temperature and the presence of harmful chemicals. Such studies would help determine the limits of survival of Earth’s multicellular organisms. This is very interesting especially in the context of searching for life on other planets and moons.


The studies were conducted in the framework of activities of the BARg (Biodiversity and Astrobiology Research group). The authors also wish to thank Cambridge Proofreading LLC ( ) and ( ) for help in improving the English in the manuscript.

This paper is part of the Special Collection of Papers from EANA 2013: The 13th European Workshop on Astrobiology, 22–25 July 2013, Szczecin, Poland (Franco Ferrari and Ewa Szuszkiewicz Guest Editors)

Contributor Information

Erdmann Weronika, Email: lp.nnamdre@akinorew .

Kaczmarek Łukasz, Email: lp.ude.uma@ramzcak .

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Frontiers for Young Minds

Frontiers for Young Minds

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Water Bears—The Most Extreme Animals on The Planet (And in Space!)

research on water bears

Can you imagine that there is an eight-legged bear that tolerates colder temperatures than the polar bears do in the Arctic? Can you imagine that this bear is able to grow older than the grizzly bears in North America? And can you imagine that this bear grows by molting, like spiders or snakes? These so-called water bears, scientifically named tardigrades, are the most extreme animals on our planet. They not only survive in ice, but also in boiling water. Moreover, they can stop breathing for long periods and they have even traveled to outer space, surviving without an astronaut’s suit. Since water bears can withstand the harshest conditions on earth and beyond, they may teach us how we can protect ourselves from extreme environmental conditions.

Are Water Bears True Bears?

What are water bears? Are they really bears? This question is easy to answer: no, the only thing that water bears and bears have in common is the fact that both are animals. The shape of a water bear slightly resembles that of true bears, such as the polar bear or the grizzly, but they are most closely related to the huge group called the arthropods , which includes insects, spiders, millipedes, and crabs. However, you cannot see a water bear with the naked eye, because these animals are very tiny. They usually grow to <1 mm ( Figure 1 ). Water bears were discovered more than 200 years ago [ 1 ]. The German pastor and biologist Johann Goeze initially named them “little water bears,” because of their size and their preference for wet living spaces.

Figure 1 - Water bears, also called tardigrades, are extremely small compared to other animals.

  • Figure 1 - Water bears, also called tardigrades, are extremely small compared to other animals.
  • This image of a water bear was taken with a scanning electron microscope. The water bear micrograph by Bob Goldstein and Vicky Madden ( ). Photographs of the grasshopper and the cat by S. Elleuche.

Water bears love wet or at least humid environments where they can remain covered by a layer of water. They are among the most successful lifeforms known and are widely distributed all over our planet. We can observe water bears in all oceans, rivers, seas, and lakes, and in wetlands , but they are mainly found in mosses or swamps. Water bears have even conquered the highest mountains, rainforests, and Antarctica. Many different types of water bears have been found and described. They even conquered Hollywood, where you may have encountered water bears in the Marvel superhero movies “Ant-Man” and “Ant-Man and the Wasp,” when Scott Lang disappears into the quantum realm.

Water bears have a strange shape—they are of stout build with four pairs of short and stubby legs, ending with four to eight claws, and they appear to lumber along as they move ( Figure 1 ). The first three pairs of legs are used for moving, while the water bears use the last pair of legs to hang on to the surface on which they walk. Even with so many legs, water bears usually do not walk but instead passively slide, using the flow of water or wind. The way they move is also reflected by their scientific name: tardigrades . Tardigradum means “slow walker,” and this name was given to water bears by Loredano Spallanzani, a former Italian biologist, due to the slow and sedate behavior of these animals, which might look like laziness.

How Do Water Bears Grow?

Just like almost any other creature on our planet, water bears must eat food and breathe air to generate the energy needed for their cells to divide and their bodies to grow. In contrast to true bears, water bears are just too tiny to eat salmon or seals. Honey is also not on their menu. Nevertheless, water bears basically eat everything. While they mainly prefer vegetarian foods like plants and algae, they will also eat microscopic animals.

Unlike most other animals, the bodies of water bears are created following a specific plan. Every type of adult water bear even has exactly the same number of cells. Their cells are continuously dividing, but the water bear is covered by a non-growing and non-flexible sheath, or protective outer covering. As soon as the sheath becomes too tight, water bears will shed the sheath in a process called molting , similar to spiders and snakes. Although both humans and water bears need oxygen to survive, water bears do not breathe the way we do. In fact, they do not even possess respiratory organs like lungs. Water bears take up air through the surfaces of their bodies, just like insects. Water bears can even stop breathing and eating for some time, similar to the process of hibernation that allows other animals, such as polar bears, to slow down their bodily processes to survive the winter months. However, water bears are even more impressive, because not only can they sleep for a couple of months, but they can also become extremely old and thrive in the most extreme places on earth.

What Are the Most Extreme Living Spaces for Water Bears?

Water bears are the most extreme animals that we know—they basically tolerate almost every extreme condition that we can think of. They can survive in the Arctic alongside polar bears, or in Antarctica, where penguins feel at home ( Figure 2A ). Water bears even survive in the laboratory at temperatures below −200°C, which is more than twice as cold as the coldest temperature that was ever observed in nature. Under such extreme conditions, the water bears enter a stage that resembles death. During this death-like resting stage, called dormancy , water bears stop all functions that usually define life: they stop breathing, they stop moving and growing, and they even stop digesting their last meal [ 2 ]. Depending on how long they are in dormancy, it can take several hours to wake them up. Some water bears have even been seen to last for a century in dormancy.

Figure 2 - (A) Water bears can survive in extremely cold habitats, like the icy Himalaya mountains, and at temperatures as low as −150°C.

  • Figure 2 - (A) Water bears can survive in extremely cold habitats, like the icy Himalaya mountains, and at temperatures as low as −150°C.
  • (B) Water bears can survive in extremely hot habitats, like the hottest deserts, and at temperatures as high as 100°C. (C) Water bears can even survive in the vacuum of space!

On the other end of the temperature scale, there are microbes that can grow at temperatures around 120°C. These heat-loving microbes are called extremophiles [ 3 , 4 ]. Water bears do not love the extreme heat, but not only can water bears survive in the desert, they can even tolerate temperatures around 150°C ( Figure 2B )—temperatures that would kill most extremophiles. Even more impressive is the fact that water bears can be repeatedly heated up and frozen without dying. These abilities have allowed water bears to become unrivaled in their success over the course of evolution. More than 1,000 different types of water bears are known, with the oldest species dating back more than 500 million years.

Water bears do not only survive the coldest cold or the hottest heat without food and without air to breathe, but they can also go without water and they are resistant to radiation. Since those extreme conditions exist in space, scientists asked themselves whether water bears might even be able to travel in space ( Figure 2C ). Scientists knew that the high pressure present in the deep sea could be tolerated by water bears, but in space there is a vacuum, with lower pressure compared to earth. Nevertheless, several species of water bears were sent into space and all of them returned home in healthy condition. Moreover, more than 1,000 water bears in dormancy were crash-landed on the moon as passengers of a spacecraft in 2019. It is expected that most of these robust animals have survived the crash and could be revived by water and oxygen in the future.

Could Water Bears Be Used to Help Humans?

For a long time, scientists have been trying to understand the water bears’ resistance to radiation. Although radiation in the form of X-rays can be used by doctors to examine broken bones, radiation can also cause the destruction of the body’s instruction manual. This instruction manual is called the genome , and it is similar in every living organism on earth, including water bears. There must be a reason for the immense resistance to radiation seen in water bears, which is more than 1,000 times higher than humans’ resistance.

One part of the genome of water bears has recently been identified and reproduced in a laboratory [ 5 ]. When this factor was added to human cells grown in the same laboratory, the human cells tolerated more intense radiation than did human cells without the water bear factor. These early experiments may lead to future applications of water bear factors that could not only be used to protect the human cells against radiation, but possibly also to stabilize drugs or to increase the resistance of crop plants to environmental conditions like drought.

What We Have Learned From Water Bears

So, now you can see that those little water bears are quite different from the bears we know well. We have learned from these animals that they not only tolerate the most extreme conditions on our planet, they are even capable to survive in Space. Because of these unique properties, water bears are fascinating and among the most interesting model organisms for us to further study.

Arthropods : ↑ This group of animals is characterized by the outer skeleton and includes insects, spiders, millipedes, and crabs.

Wetland : ↑ A living space for multiple organisms that is temporary or permanently flooded by water and inhabited by aquatic plants.

Tardigrade : ↑ A scientific nomenclature for a group of animals that are also known as water bears or moss piglets.

Molting : ↑ Some animals, such as water bears, insects, spiders and snakes do not grow continuously. They have to replace their outer sheath when it became too tight.

Dormancy : ↑ Death-like resting stage during which each kind of activity such as growth or ingestion is temporarily stopped.

Extremophiles : ↑ Microorganisms that love to live in the most extreme environments on the planet. Water bears are no true extremophiles because, although they can tolerate extreme conditions, they do not prefer such environments.

Genome : ↑ A kind of construction plan that is included in every living cell in all organisms (Bacteria, Fungi, Plants, Animals etc.), which determines the look and composition of most cellular compon.

Conflict of Interest

The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The author thanks Sylvia Wiese and Jan Friesen for critically reading the manuscript.

[1] ↑ Jönsson, K. I. 2019. Radiation tolerance in tardigrades: current knowledge and potential applications in medicine. Cancers 11:1333. doi: 10.3390/cancers11091333

[2] ↑ Fontaneto, D. 2019. Long-distance passive dispersal in microscopic aquatic animals. Mov. Ecol . 7:10. doi: 10.1186/s40462-019-0155-7

[3] ↑ Elleuche, S., Schröder, C., Stahlberg, N., and Antranikian, G. 2017. “Boiling water is not too hot for us!”—preferred living spaces of heat-loving microbes. Front. Young Minds . 5:1. doi: 10.3389/frym.2017.00001

[4] ↑ Schröder, C., Burkhardt, C., Antranikian, G. 2020. What we learn from extremophiles. ChemTexts 6:8. doi: 10.1007/s40828-020-0103-6

[5] ↑ Hashimoto, T., Horikawa, D. D., Saito, Y., Kuwahara, H., Kozuka-Hata, H., Shin, I. T., et al. 2016. Extremotolerant tardigrade genome and improved radiotolerance of human cultured cells by tardigrade-unique protein. Nat. Commun . 7:12808. doi: 10.1038/ncomms12808

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Tardigrades (Water Bears)

Created by Sarah Bordenstein, Marine Biological Laboratory

Strange is this little animal, because of its exceptional and strange morphology and because it closely resembles a bear en miniature. That is the reason why I decided to call it little water bear.

- J.A.E. Goeze (Pastor at St. Blasii, Quedlinburg, Germany), 1773

What is a Tardigrade - Where to Find - How to Find - Tardigrades in Extreme Environments - Resources  

What is a Tardigrade?

Tardigrade, or Water Bear

Tardigrades (Tardigrada), also known as water bears or moss piglets , are a phylum of small invertebrates. They were first described by the German pastor J.A.E. Goeze in 1773 and given the name Tardigrada, meaning "slow stepper," three years later by the Italian biologist Lazzaro Spallanzani. Tardigrades are short (0.05mm - 1.2mm in body length), plump, bilaterally symmetrical, segmented organisms. They have four pairs of legs, each of which ends in four to eight claws. Tardigrades reproduce via asexual ( parthenogenesis ) or sexual reproduction and feed on the fluids of plant cells, animal cells, and bacteria. They are prey to amoebas, nematodes, and other tardigrades. Some species are entirely carnivorous! Tardigrades are likely related to Arthropoda (which includes insects, spiders, and crustaceans) and Onychophora (velvet worms), and are often referred to as a "lesser known taxa" of invertebrates . Despite their peculiar morphology and amazing diversity of habitats, relatively little is known about these tiny animals. This makes them ideal research subjects for which students and amateur microscopists may contribute novel data to the field.

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Where to Find Tardigrades

Tardigrades can be found in almost every habitat on Earth! With over 900 ( more info ) described species, the phylum has been sighted from mountaintops to the deep sea, from tropical rain forests to the Antarctic. Most species live in freshwater or semiaquatic terrestrial environments, while about 150 marine species have been recorded. All Tardigrades are considered aquatic because they need water around their bodies to permit gas exchange as well as to prevent uncontrolled desiccation. They can most easily be found living in a film of water on lichens and mosses, as well as in sand dunes, soil, sediments, and leaf litter.

Moss on the walls of Zion Canyon

How to Find Terrestrial Tardigrades

  • Collect a clump of moss or lichen (dry or wet) and place in a shallow dish, such as a Petri dish.
  • Soak in water (preferably rainwater or distilled water) for 3-24 hours.
  • Remove and discard excess water from the dish.
  • Shake or squeeze the moss/lichen clumps over another transparent dish to collect trapped water.
  • Starting on a low obejctive lens, examine the water using a stereo microscope.
  • The Water Bear web base
  • Hunting for Bears in the Backyard

Tardigrades in Extreme Environments


  • temperatures as low as -200 ° C (-328 ° F) and as high as 151 ° C (304 ° F);
  • freezing and/or thawing processes;
  • changes in salinity;
  • lack of oxygen;
  • lack of water;
  • levels of X-ray radiation 1000x the lethal human dose;
  • some noxious chemicals;
  • boiling alcohol;
  • low pressure of a vacuum;
  • high pressure (up to 6x the pressure of the deepest part of the ocean).

How do they do it?

Tardigrades have adapted to environmental stress by undergoing a process known as cryptobiosis . Cryptobiosis is defined as a state in which metabolic activities come to a reversible standstill. It is truly a death-like state; most organisms die by a cessation of metabolism. Several types of cryptobiosis exist, the most common include:

  • anhydrobiosis (lack of water);
  • cryobiosis (low temperature);
  • osmobiosis (increased solute concentration, such as salt water);
  • anoxybiosis (lack of oxygen).

The most common type of cryptobiosis studied in tardigrades is anhydrobiosis. Anton van Leeuwenhoek first documented cryptobiosis in 1702, when he observed tiny animalcules in sediment collected from house roofs. He dried them out, added water, and found that the animals began moving around again. The animalcules were likely nematodes or rotifers, other types of cryptobiotic animals. Tardigrades can survive dry periods by curling up into a little ball called a tun. Tun formation requires metabolism and synthesis of a protective sugar known as trehalose, which moves into the cells and replaces lost water. While in a tun, their metabolism can lower to less than 0.01% of normal. Revival typically takes a few hours, depending on how long the tardigrade has been in the cryptobiotic state.

Live tardigrades have been regenerated from dried moss kept in a museum for over 100 years! Once the moss was moistened, they successfully recovered from their tuns. While tardigrades can survive in extreme environments, they are not considered extremophiles because they are not adapted to live in these conditions. Their chances of dying increase the longer they are exposed to the extreme environment.

Hypsibius augusti, a Tardigrade

Learn more about Tardigrades with this collection of resources including informational websites, primary literature, and educational activities.

Additional Resources

For additional resources about Tardigrades, search the Microbial Life collection.

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January 17, 2024

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Molecular sensor enables water bear hardiness by triggering dormancy, study finds

by Public Library of Science

Molecular sensor enables water bear hardiness by triggering dormancy

Tardigrades—hardy, microscopic animals commonly known as "water bears"—use a molecular sensor that detects harmful conditions in their environment, telling them when to go dormant and when to resume normal life. A team led by Derrick R. J. Kolling of Marshall University and Leslie M. Hicks of the University of North Carolina at Chapel Hill report these findings in a study published in the open-access journal PLOS ONE .

Water bears are famous for their ability to withstand extreme conditions , and can survive freezing, radiation, and environments without oxygen or water. They persist by going dormant and entering a tun state, in which their bodies become dehydrated, their eight legs retract and their metabolism slows to almost undetectable levels. Previously, little was known about what signals water bears to enter and leave this state.

In the new study, researchers exposed water bears to freezing temperatures or high levels of hydrogen peroxide, salt or sugar to trigger dormancy. In response to these harmful conditions, the animals' cells produced damaging oxygen free radicals.

The researchers found that water bears use a molecular sensor—based on the amino acid cysteine —which signals the animals to enter the tun state when it is oxidized by oxygen free radicals. Once conditions improve and the free radicals disappear, the sensor is no longer oxidized, and the water bears emerge from dormancy.

When the researchers applied chemicals that block cysteine, the water bears could not detect the free radicals and failed to go dormant.

Altogether, the new results indicate that cysteine is a key sensor for turning dormancy on and off in response to multiple stressors, including freezing temperatures, toxins and concentrated levels of salt or other compounds in the environment. The findings suggest that cysteine oxidation is a vital regulatory mechanism that contributes to water bears' remarkable hardiness and helps them survive in ever-changing environments.

The authors add, "Our work reveals that tardigrade survival to stress conditions is dependent on reversible cysteine oxidation, through which reactive oxygen species serve as a sensor to enable tardigrades to respond to external changes."

Journal information: PLoS ONE

Provided by Public Library of Science

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Tardigrades – Water Bear

Survivalists at the Micro Level: The Amazing World of Tardigrades

Welcome to the incredible microcosm of survivalists – tardigrades. Known as water bears, these microscopic marvels defy the limits of endurance in the most challenging environments. From the deep sea to towering mountains, tardigrades showcase unparalleled adaptability. In this exploration, we unravel the secrets behind their resilience, cryptobiosis mastery, and survival in space, unveiling the amazing world of tardigrades as true champions at the micro level.

Microscopic Wonders

Tardigrades, affectionately termed water bears, are exceptional microscopic organisms, epitomizing extraordinary resilience. Despite their diminutive size, these creatures exhibit an unparalleled ability to withstand extreme conditions, navigating environments where others falter. From the depths of the ocean to the highest mountain peaks, tardigrades showcase a tenacity that defies their minuscule stature. Colloquially celebrated as water bears, these microscopic wonders capture the essence of survival at the micro level, embodying an awe-inspiring ability to endure and thrive in the face of challenges that surpass the limits of larger organisms.

Diverse Habitats

Tardigrades, commonly known as water bears, emerge as masters of adaptation, thriving across a spectrum of diverse habitats that span the Earth’s extremes. From the lightless depths of the deep sea to the lofty heights of mountainous terrains, these microscopic marvels showcase an unparalleled adaptability to the harshest conditions nature offers.

In the ocean’s abyssal plains, tardigrades navigate the crushing pressures, demonstrating a resilience that sets them apart. Scaling mountainous landscapes, they endure oxygen-thin air and temperature extremes. Tardigrades are equally at home in mosses, lichens, and leaf litter, showcasing their ability to persist in microenvironments that pose challenges to most life forms.

The astounding adaptability of tardigrades across such diverse ecosystems reflects their prowess in conquering extremes. This adaptability not only fuels their survival but also positions them as extraordinary indicators of life’s potential in environments deemed inhospitable to many. As we explore their presence in various habitats, we gain a profound appreciation for the resilience and versatility that define these microcosmic survivalists.

Resilience Unveiled

Tardigrades, colloquially known as water bears, reveal a profound mystery in the realm of resilience, defying conventional limits and thriving where few organisms dare to venture. This microscopic wonder unfolds a tale of unparalleled endurance, showcasing the secrets behind their ability to withstand extreme conditions. Whether subjected to harsh temperatures, intense pressures, or the vacuum of space, tardigrades stand resilient, unraveling nature’s secrets of survival at a scale that challenges our understanding. The water bear’s resilience unveils a microcosmic marvel, inviting us to explore the extraordinary mechanisms that enable them to triumph in the face of adversity.

Cryptobiosis Mastery

Tardigrades, the microscopic marvels often referred to as water bears, wield an extraordinary survival strategy – cryptobiosis. In this remarkable state, they adeptly shut down their metabolism, a feat that enables them to endure the harshest conditions, including desiccation. This microcosmic mastery allows water bears to suspend their biological activities, essentially entering a state of suspended animation. Cryptobiosis emerges as the key to their resilience, unveiling a fascinating adaptation that empowers tardigrades to navigate extreme environments and persevere in the face of challenges that would spell doom for many other life forms.

Space Survivors:

Embark on a cosmic journey with tardigrades, the resolute water bears, as they venture into the inhospitable realms of outer space and emerge as extraordinary space survivors. In pioneering experiments, these microscopic marvels have defied the odds, enduring the vacuum and radiation of space aboard spacecraft. Strapped to the exterior of satellites and shuttles, tardigrades have withstood the harsh conditions, showcasing an incredible resilience that challenges our perceptions of life’s fragility beyond Earth. As space travelers, they offer insights into the potential for life to endure in extraterrestrial environments, inspiring awe and curiosity about the microorganisms that defy the cosmic challenges of the void.

Biological Adaptability: 

Tardigrades, endearingly known as water bears, unveil a stunning display of biological adaptability, demonstrating an unparalleled ability to persist in diverse and hostile environments. These diminutive creatures navigate extremes with remarkable ease, showcasing a versatility that defies conventional limits. From the depths of the ocean to the peaks of mountains, tardigrades embody an exceptional adaptability that allows them to thrive where others struggle. Their ability to confront and conquer varied challenges reflects a microcosmic triumph of biological resilience, offering a testament to nature’s ingenuity in creating life forms capable of flourishing in the most contrasting landscapes.

Anhydrobiosis Feat:

Delve into the extraordinary phenomenon of anhydrobiosis, a captivating survival strategy mastered by tardigrades, the resilient water bears. In this remarkable process, these microscopic marvels can shed almost all body water content, entering a desiccated state, only to spring back to life upon rehydration. Anhydrobiosis allows tardigrades to withstand extreme dehydration, navigating environments where water scarcity would typically be lethal. Witnessing this feat of desiccation tolerance unveils a microcosmic spectacle of adaptation, where tardigrades seemingly defy the constraints of conventional life, showcasing a remarkable ability to suspend life processes and revive when conditions once again become conducive.

Scientific Marvels:

Tardigrades, often affectionately called water bears, emerge as true scientific marvels, unravelling mysteries that captivate researchers and broaden our understanding of extremophiles and life’s potential in extreme environments. These microscopic organisms, with their unparalleled resilience, become invaluable subjects of study, providing critical insights into the boundaries of life on Earth and beyond.

As extremophiles, tardigrades redefine our understanding of where life can thrive. Their ability to endure extreme temperatures, pressures, and even the vacuum of space positions them as extraordinary contributors to astrobiology and the exploration of extraterrestrial life.

Studying tardigrades not only expands our knowledge of these microscopic marvels but also fuels scientific curiosity about the adaptability of life in the cosmos. In unlocking the secrets held by water bears, scientists glimpse into the intricacies of survival, resilience, and the potential for life to persist in the most challenging corners of the universe. Tardigrades stand at the intersection of scientific fascination, offering a gateway to exploring the frontiers of life’s tenacity and adaptability in environments previously thought uninhabitable.

Microbial Survivors:

Acknowledging the microscopic wonders known as tardigrades reveals an extraordinary narrative of tiny survivors contributing significantly to our understanding of microbial survival strategies. These water bears, though minuscule, play a pivotal role in unraveling the intricacies of how microorganisms persist in diverse and often challenging environments.

Tardigrades, with their resilience to extreme conditions, act as ambassadors for microbial life, showcasing adaptability that transcends the limitations of size. By navigating the abyssal depths of the sea, scaling towering mountains, and even braving the rigors of outer space, these microbial survivors become invaluable subjects in the exploration of microbial survival tactics.

Understanding the strategies employed by tardigrades sheds light on the broader realm of microbial life. Their ability to withstand desiccation, endure radiation, and thrive in various ecosystems underscores the versatility of microbial survival. As we acknowledge the significance of tardigrades, we gain insights into the fundamental mechanisms that govern microbial resilience, fostering a deeper appreciation for the myriad ways these tiny survivors contribute to the intricate tapestry of life on our planet and, potentially, beyond.


In delving into the amazing world of tardigrades, the microscopic survivalists, we unveil a testament to nature’s ingenuity and the resilience of life at the micro level. From the depths of the ocean to the vastness of outer space, these water bears defy conventional limits, showcasing unparalleled adaptability and survival strategies.

Tardigrades, with their mastery of cryptobiosis, endurance in space, and ability to navigate extreme environments, stand as extraordinary ambassadors of microbial resilience. Their significance extends beyond their diminutive size, offering valuable insights into extremophiles and challenging our understanding of where life can thrive.

As we conclude this exploration, we acknowledge the exceptional role tardigrades play in advancing scientific knowledge. Their microcosmic triumphs inspire awe and curiosity, inviting us to ponder the broader implications for life’s potential in the universe. Tardigrades, the unsung heroes of microscopic survival, continue to illuminate the wonders of life at the smallest scales, leaving an indelible mark on the scientific landscape.

  • A: Tardigrades, colloquially known as water bears, are microscopic, water-dwelling animals known for their resilience.
  • A: Tardigrades inhabit diverse environments, including mosses, lichens, leaf litter, deep-sea environments, and even outer space.
  • A: Tardigrades earned the nickname “water bears” due to their lumbering movement reminiscent of a bear’s walk.
  • A: Cryptobiosis is a state where tardigrades suspend their metabolism, enabling them to survive extreme conditions like desiccation.
  • A: Yes, tardigrades have demonstrated the ability to survive the vacuum and radiation of outer space.
  • A: Tardigrades have been discovered in a wide range of environments, from the deep sea to high mountain peaks.

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What is a tardigrade?

Tardigrade, SEM

Tardigrades are tiny, cute and virtually indestructible. The microscopic animals are able to survive in a pot of boiling water , at the bottom of a deep-sea trench or even in the cold, dark vacuum of space. In August, an Israeli spacecraft carrying tardigrades as part of a scientific experiment crashed on the moon, and scientists believe they may have survived .

The hundreds of species belonging to the phylum Tardigrada are so hardy that many could be here long after other life on Earth has perished , enduring as long as the sun continues to shine. It’s this uncanny ability to endure extreme conditions that has drawn the attention of scientists, who say tardigrades may hold the key to human survival. What we learn from ongoing research on tardigrades could help us stay alive on the operating table or in outer space.

What do tardigrades look like?

Tardigrades have long, plump bodies and eight stubby legs. They’re closely related to insects and crustaceans but look a bit like pigs or bears — and are sometimes called “water bears.”

“Their proportions are a little bit similar to a bear’s, and they’re kind of cute — at least some of them are cute to some people," Roger Chang, a Harvard University molecular biologist who studies tardigrades, said.

Most tardigrade species are less than half a millimeter long, around the size of a dust mite. Some species are larger, growing up to 1.5 millimeters, around the size of a grain of sand — big enough to be seen with the naked eye, according to Chang.

Where do tardigrades live?

Tardigrades are semi-aquatic. They can survive in watery as well as terrestrial environments — from oceans and lakes to mountains, forests and sand dunes. They're found all over the world, from frigid Antarctic glaciers to active lava fields . They’re most commonly found living in moss.

Most tardigrades eat algae and flowering plants, piercing plant cells and sucking out their contents though their tube-shaped mouths. Some, however, are carnivorous and may eat other tardigrades.

Tardigrades are nature’s pioneers, colonizing new, potentially harsh environments , providing food for larger creatures that follow. Scientists say, for instance, that tardigrades may have been among the first animals to leave the ocean and settle on dry land .

Tardigrades pose no threat to humans. Scientists have yet to identify a species of tardigrade that spreads disease.

What's the lifespan of a tardigrade?

Tardigrades typically live for only a few months when fully active. When short on water, they may curl up in a ball, entering the “tun” state — so named because it looks like a large barrel called a “tun.”

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In this state, a tardigrade grows a glass-like protective coating and slows its metabolism to 0.01 percent of the usual rate. Chang said a tardigrade could potentially survive for centuries like this, though it wouldn’t be much of a life. The tun state looks more like a temporary death than a long hibernation.

“What do you call alive, exactly?” Chang said. “It’s kind of a matter of semantics.”

Are tardigrades immortal?

In their active state, tardigrades are decidedly mortal. Chang said he has accidentally killed countless tardigrades by starving them or drying them out too fast. Once he inadvertently sent a test tube full of them through an airport security scanner.

“They are actually relatively easy to kill when they’re not in this tun state,” he said. “They are really just as fragile as most microscopic animals.”

As tuns, however, tardigrades can endure radiation , extreme pressure and extreme heat and cold, including temperatures near absolute zero.

Scientists have subjected tardigrades to all manner of insult to test their hardiness. For one study, Japanese researchers froze tardigrades for 30 years before reviving them and watching them reproduce. For another, the European Space Agency sent tardigrades into space to see how they would cope with solar radiation — and a handful actually managed to survive.

How are tardigrades used in scientific research?

German pastor J.A.E. Goeze published the first paper on tardigrades in 1773 . Scientists have long studied the creatures to better understand how animals could persist in the most hostile environments. In recent years, researchers have been working to apply what they learned to humans.

Chang and his colleagues hope to imbue humans cells with a tardigrade’s ability to shut down temporarily, aiming to develop synthetic proteins like those discharged by water bears as they enter the tun state. These synthetic proteins could be used, for example, to preserve organs needed for transplants, potentially keeping organs viable for longer than is possible by storing them on ice.

Someday it may be possible to use what we learn from tardigrades to aid victims of strokes or heart attack by protecting their vital organs against further damage as they await treatment, or to help technicians working in nuclear power plants to guard against radiation , or conceivably, to help astronauts to survive on long spaceflights.

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Study determines microscopic water bears will be Earth’s last survivors

In Animals , Marine Science , Research News , Science & Nature , Space , Spotlight / 19 July 2017

By Megan Watzke


The world’s most indestructible species, the tardigrade, an eight-legged micro-animal, also known as the water bear, will survive until the Sun dies, according to a new Harvard-Smithsonian Center for Astrophysics and Oxford University collaboration.

The world’s most indestructible species, the tardigrade, an eight-legged micro-animal, also known as the water bear, will survive until the Sun dies, according to a new Harvard-Smithsonian Center for Astrophysics and Oxford University collaboration.

The new study published in Scientific Reports, has shown that the tiny creatures will survive the risk of extinction from all astrophysical catastrophes, and be around for at least 10 billion years–far longer than the human race.

Although much attention has been given to the cataclysmic impact that an astrophysical event would have on human life, very little has been published around what it would take to kill the tardigrade, and wipe out life on this planet. The research implies that life on Earth in general, will extend as long as the Sun keeps shining. It also reveals that once life emerges, it is surprisingly resilient and difficult to destroy, opening the possibility of life on other planets.

Tardigrades are the toughest, most resilient form of life on earth, able to survive for up to 30 years without food or water, and endure temperature extremes of up to 150 degrees Celsius, the deep sea and even the frozen vacuum of space. The water-dwelling micro animal can live for up to 60 years, and grow to a maximum size of 0.5 mm, best seen under a microscope.

Researchers from the Universities of Oxford and the Harvard-Smithsonian Center for Astrophysics, have found that these life forms will likely survive all astrophysical calamities, such as an asteroid, since they will never be strong enough to boil off the world’s oceans.

Three potential events were considered as part of the research, including; large asteroid impact, and exploding stars in the form of supernovas or gamma-ray bursts.

Asteroids:   There are only a dozen known asteroids and dwarf planets with enough mass to boil the oceans, these include Vesta and Pluto, however none of these objects will intersect the Earth’s orbit and pose no threat to tardigrades.

Supernova:  In order to boil the oceans an exploding star would need to be 0.14 light-years away. The closest star to the Sun is four light years away and the probability of a massive star exploding close enough to Earth to kill all forms of life on it, within the Sun’s lifetime, is negligible.

Gamma-Ray bursts:  Gamma-ray bursts are brighter and rarer than supernovae. Much like supernovas, gamma-ray bursts are too far away from earth to be considered a viable threat. To be able to boil the world’s oceans the burst would need to be no more than 40 light-years away, and the likelihood of a burst occurring so close is again, minor.

“Without our technology protecting us, humans are a very sensitive species. Subtle changes in our environment impact us dramatically. There are many more resilient species’ on earth. Life on this planet can continue long after humans are gone,” says Rafael Alves Batista, co-author and post-doctoral research associate in the Department of Physics at Oxford University. “Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the universe. In this context there is a real case for looking for life on Mars and in other areas of the solar system in general. If tardigrades are Earth’s most resilient species, who knows what else is out there.”

David Sloan, co-author and post-doctoral research associate in the Department of Physics at Oxford University, said: “To our surprise we found that although nearby supernovae or large asteroid impacts would be catastrophic for people, tardigrades could be unaffected. Therefore it seems that life, once it gets going, is hard to wipe out entirely. Huge numbers of species, or even entire genera may become extinct, but life as a whole will go on.”

In highlighting the resilience of life in general, the research broadens the scope of life beyond Earth, within and outside of this solar system. Abraham Loeb, co-author and chair of the Astronomy Department at Harvard University, said: “It is difficult to eliminate all forms of life from a habitable planet. Organisms with similar tolerances to radiation and temperature as tardigrades could survive long-term below the surface in these conditions. The subsurface oceans that are believed to exist on Europa and Enceladus, would have conditions similar to the deep oceans of Earth where tardigrades are found, volcanic vents providing heat in an environment devoid of light. The discovery of extremophiles in such locations would be a significant step forward in bracketing the range of conditions for life to exist on planets around other stars.”

A paper detailing this work appeared on July 14, 2017 in Scientific Reports , an open, online journal from the publishers of Nature.

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Meet the water bear, Earth’s indestructible animal that will outlive us all

by Gordon Hunt

14 Jul 2017

A tardigrade, or water bear. Image: 3Dstock/Shutterstock

A tardigrade, or water bear. Image: 3Dstock/Shutterstock

There are endless ways to end the human race, with gentle changes to our environment enough to push us over the edge. Not the tardigrade, though. It’s here to stay.

There is plenty of research already looking into apocalyptic events on Earth, with humans potentially wiped out by temperature rises, temperature falls, meteorites, super volcanoes and sea rises. But what about our planet’s hardier species?

Cockroaches are notoriously strong, and ants can handle a fair bit of discomfort, too. But what of the tardigrade? Otherwise known as a water bear, these water-dwelling, eight-legged, segmented micro-animals are as close to an indestructible being as we have on Earth.

For example, last year , it emerged that they could survive for up to 30 years, frozen, without food or water, and could even be brought back to functioning life.

They can endure temperature extremes of up to 150 degrees Celsius, the deep sea and even the frozen vacuum of space. The animal can live for up to 60 years, and grow to a maximum size of 0.5mm, best seen under a microscope.

And now, according to a study in England, they win the prize for ‘most likely to survive an apocalypse’.

Bye bye, humans

Researchers from Oxford could find little or no way to eliminate the water bear from Earth, predicting a lifetime of around 10bn years.

This strengthens interest in the hunt for life on other planets, with Dr Rafael Alves Batista, co-author of the paper, wondering what else is out there.

A postdoctoral research associate at the Department of Physics at University of Oxford, Batista’s study looked at three possible life extinction events, and how water bears may handle the effects.

The research established that the only possible way to eliminate all water bears would be to boil away all of the Earth’s oceans, as neither meteorites (too few), nor star supernovae or gamma-ray bursts (both too far away) would get the job done.

“Without our technology protecting us, humans are a very sensitive species,” said Batista, noting that even subtle environmental changes can have a devastating effect on us.

“There are many more resilient species on Earth. Life on this planet can continue long after humans are gone.

“Tardigrades are as close to indestructible as it gets on Earth, but it is possible that there are other resilient species examples elsewhere in the universe.

“In this context, there is a real case for looking for life on Mars and in other areas of the solar system in general. If tardigrades are Earth’s most resilient species, who knows what else is out there?”

Martian law

The trio of Earth-shattering events investigated would spell the end for humans, no question. However, water bears surviving each and every one of them shows just how resilient life is, once it gets a foothold on a planet.

Prof Abraham Loeb, co-author and chair of the Department of Astronomy at Harvard University, suggested that Mars’ history of once having a somewhat habitable environment means that our focus should be on the Red Planet.

With NASA’s ongoing efforts to send humans to Mars, and a series of rovers already pottering about on Martian soil, this makes even more sense.

The potential for life grows even more when we consider the oceans of water predicted on various moons in our solar system, Europa and Enceladus in particular.

“The discovery of extremophiles in such locations would be a significant step forward in bracketing the range of conditions for life to exist on planets around other stars,” said Loeb, with the paper published this week in Scientific Reports .

Related: Earth , planets , microbiology , biology , research

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Gordon Hunt was a journalist with Silicon Republic

[email protected]

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The Effects of Climate Change

The effects of human-caused global warming are happening now, are irreversible for people alive today, and will worsen as long as humans add greenhouse gases to the atmosphere.

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  • We already see effects scientists predicted, such as the loss of sea ice, melting glaciers and ice sheets, sea level rise, and more intense heat waves.
  • Scientists predict global temperature increases from human-made greenhouse gases will continue. Severe weather damage will also increase and intensify.

Earth Will Continue to Warm and the Effects Will Be Profound


Global climate change is not a future problem. Changes to Earth’s climate driven by increased human emissions of heat-trapping greenhouse gases are already having widespread effects on the environment: glaciers and ice sheets are shrinking, river and lake ice is breaking up earlier, plant and animal geographic ranges are shifting, and plants and trees are blooming sooner.

Effects that scientists had long predicted would result from global climate change are now occurring, such as sea ice loss, accelerated sea level rise, and longer, more intense heat waves.

The magnitude and rate of climate change and associated risks depend strongly on near-term mitigation and adaptation actions, and projected adverse impacts and related losses and damages escalate with every increment of global warming.

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Intergovernmental Panel on Climate Change

Some changes (such as droughts, wildfires, and extreme rainfall) are happening faster than scientists previously assessed. In fact, according to the Intergovernmental Panel on Climate Change (IPCC) — the United Nations body established to assess the science related to climate change — modern humans have never before seen the observed changes in our global climate, and some of these changes are irreversible over the next hundreds to thousands of years.

Scientists have high confidence that global temperatures will continue to rise for many decades, mainly due to greenhouse gases produced by human activities.

The IPCC’s Sixth Assessment report, published in 2021, found that human emissions of heat-trapping gases have already warmed the climate by nearly 2 degrees Fahrenheit (1.1 degrees Celsius) since 1850-1900. 1 The global average temperature is expected to reach or exceed 1.5 degrees C (about 3 degrees F) within the next few decades. These changes will affect all regions of Earth.

The severity of effects caused by climate change will depend on the path of future human activities. More greenhouse gas emissions will lead to more climate extremes and widespread damaging effects across our planet. However, those future effects depend on the total amount of carbon dioxide we emit. So, if we can reduce emissions, we may avoid some of the worst effects.

The scientific evidence is unequivocal: climate change is a threat to human wellbeing and the health of the planet. Any further delay in concerted global action will miss the brief, rapidly closing window to secure a liveable future.

Here are some of the expected effects of global climate change on the United States, according to the Third and Fourth National Climate Assessment Reports:

Future effects of global climate change in the United States:

sea level rise

U.S. Sea Level Likely to Rise 1 to 6.6 Feet by 2100

Global sea level has risen about 8 inches (0.2 meters) since reliable record-keeping began in 1880. By 2100, scientists project that it will rise at least another foot (0.3 meters), but possibly as high as 6.6 feet (2 meters) in a high-emissions scenario. Sea level is rising because of added water from melting land ice and the expansion of seawater as it warms. Image credit: Creative Commons Attribution-Share Alike 4.0

Sun shining brightly over misty mountains.

Climate Changes Will Continue Through This Century and Beyond

Global climate is projected to continue warming over this century and beyond. Image credit: Khagani Hasanov, Creative Commons Attribution-Share Alike 3.0

Satellite image of a hurricane.

Hurricanes Will Become Stronger and More Intense

Scientists project that hurricane-associated storm intensity and rainfall rates will increase as the climate continues to warm. Image credit: NASA

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More Droughts and Heat Waves

Droughts in the Southwest and heat waves (periods of abnormally hot weather lasting days to weeks) are projected to become more intense, and cold waves less intense and less frequent. Image credit: NOAA

2013 Rim Fire

Longer Wildfire Season

Warming temperatures have extended and intensified wildfire season in the West, where long-term drought in the region has heightened the risk of fires. Scientists estimate that human-caused climate change has already doubled the area of forest burned in recent decades. By around 2050, the amount of land consumed by wildfires in Western states is projected to further increase by two to six times. Even in traditionally rainy regions like the Southeast, wildfires are projected to increase by about 30%.

Changes in Precipitation Patterns

Climate change is having an uneven effect on precipitation (rain and snow) in the United States, with some locations experiencing increased precipitation and flooding, while others suffer from drought. On average, more winter and spring precipitation is projected for the northern United States, and less for the Southwest, over this century. Image credit: Marvin Nauman/FEMA

Crop field.

Frost-Free Season (and Growing Season) will Lengthen

The length of the frost-free season, and the corresponding growing season, has been increasing since the 1980s, with the largest increases occurring in the western United States. Across the United States, the growing season is projected to continue to lengthen, which will affect ecosystems and agriculture.

Heatmap showing scorching temperatures in U.S. West

Global Temperatures Will Continue to Rise

Summer of 2023 was Earth's hottest summer on record, 0.41 degrees Fahrenheit (F) (0.23 degrees Celsius (C)) warmer than any other summer in NASA’s record and 2.1 degrees F (1.2 C) warmer than the average summer between 1951 and 1980. Image credit: NASA

Satellite map of arctic sea ice.

Arctic Is Very Likely to Become Ice-Free

Sea ice cover in the Arctic Ocean is expected to continue decreasing, and the Arctic Ocean will very likely become essentially ice-free in late summer if current projections hold. This change is expected to occur before mid-century.

U.S. Regional Effects

Climate change is bringing different types of challenges to each region of the country. Some of the current and future impacts are summarized below. These findings are from the Third 3 and Fourth 4 National Climate Assessment Reports, released by the U.S. Global Change Research Program .

  • Northeast. Heat waves, heavy downpours, and sea level rise pose increasing challenges to many aspects of life in the Northeast. Infrastructure, agriculture, fisheries, and ecosystems will be increasingly compromised. Farmers can explore new crop options, but these adaptations are not cost- or risk-free. Moreover, adaptive capacity , which varies throughout the region, could be overwhelmed by a changing climate. Many states and cities are beginning to incorporate climate change into their planning.
  • Northwest. Changes in the timing of peak flows in rivers and streams are reducing water supplies and worsening competing demands for water. Sea level rise, erosion, flooding, risks to infrastructure, and increasing ocean acidity pose major threats. Increasing wildfire incidence and severity, heat waves, insect outbreaks, and tree diseases are causing widespread forest die-off.
  • Southeast. Sea level rise poses widespread and continuing threats to the region’s economy and environment. Extreme heat will affect health, energy, agriculture, and more. Decreased water availability will have economic and environmental impacts.
  • Midwest. Extreme heat, heavy downpours, and flooding will affect infrastructure, health, agriculture, forestry, transportation, air and water quality, and more. Climate change will also worsen a range of risks to the Great Lakes.
  • Southwest. Climate change has caused increased heat, drought, and insect outbreaks. In turn, these changes have made wildfires more numerous and severe. The warming climate has also caused a decline in water supplies, reduced agricultural yields, and triggered heat-related health impacts in cities. In coastal areas, flooding and erosion are additional concerns.

1. IPCC 2021, Climate Change 2021: The Physical Science Basis , the Working Group I contribution to the Sixth Assessment Report, Cambridge University Press, Cambridge, UK.

2. IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

3. USGCRP 2014, Third Climate Assessment .

4. USGCRP 2017, Fourth Climate Assessment .

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A Degree of Difference

So, the Earth's average temperature has increased about 2 degrees Fahrenheit during the 20th century. What's the big deal?

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What’s the difference between climate change and global warming?

“Global warming” refers to the long-term warming of the planet. “Climate change” encompasses global warming, but refers to the broader range of changes that are happening to our planet, including rising sea levels; shrinking mountain glaciers; accelerating ice melt in Greenland, Antarctica and the Arctic; and shifts in flower/plant blooming times.

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Is it too late to prevent climate change?

Humans have caused major climate changes to happen already, and we have set in motion more changes still. However, if we stopped emitting greenhouse gases today, the rise in global temperatures would begin to flatten within a few years. Temperatures would then plateau but remain well-elevated for many, many centuries.

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To Save Sun Bears, Scientists First Have to Find Them

The world’s smallest bear plays a crucial role in repairing its tropical habitat in Southeast Asia

Sun bears are named for a gold crescent on their chest, resembling a rising or setting sun. Each bear’s patch is unique, like a fingerprint.

Sun bears are named for a gold crescent on their chest, resembling a rising or setting sun. Each bear’s patch is unique, like a fingerprint.

By Alex Fox

Photograph by Sebastian Kennerknecht

The world’s smallest bear weighs as little as 60 pounds when fully grown, but it exerts a mighty influence on the patches of rainforest it inhabits across mainland Southeast Asia and the islands of Sumatra and Borneo. “Sun bears are forest engineers,” says Roshan Guharajan, a researcher with the conservation organization Panthera in Malaysian Borneo. Wong Siew Te, founder of the Bornean Sun Bear Conservation Center , calls them “forest doctors.”

They use powerful jaws and canines as large as a polar bear’s to bite chunks out of trees to access beehives, slurping the honey with a tongue that can stretch to ten inches long. The hollows they create provide new habitat for other arboreal forest dwellers such as flying squirrels or hornbills. Their short, muscled limbs and four-inch claws can break apart rotting logs for grubs and beetles, and dig for worms, boosting decomposition and cycling nutrients in the thin topsoil. And when fruits such as figs or even spiky durian are available, the bears feast on the cornucopia and disperse the seeds in their droppings as they roam, helping the forest regenerate. When fruit isn’t in season, they ransack termite nests, protecting the trees from the destructive insects.

In recent decades, however, their tropical forest homes have been slashed for timber and cleared to create palm oil plantations, especially in Malaysia and Indonesia. The bears are also poached for parts—their gallbladders contain bile used in traditional Chinese medicine, and their paws are a culinary delicacy—and they are even captured for the exotic pet trade. As a result, sun bear populations have plummeted by an estimated 35 percent or more in the last three decades.

But the bears are woefully understudied. With no reliable estimates of their global population or current distribution, conservationists are sometimes forced to guess where to protect rainforest habitat or crack down on poaching. That’s why later this year members of the International Union for Conservation of Nature’s Bear Specialist Group will launch a new initiative to create an updated range map for this little-studied species. The effort will combine new data from camera traps, field surveys and input from hundreds of experts across Southeast Asia to determine local sun bear presence. It will also use confirmed bear sightings to create a computer model that predicts where else bears “should be” by looking for environmental commonalities—attributes such as tree cover, tree species, forest age and elevation, and the locations of roads and protected area boundaries.

The specialist group will use the resulting updated range map to identify the highest-priority areas for sun bear conservation—for example, flagging emerging deforestation threats, identifying dangerously small populations and spotting corridors that could connect isolated bear habitats. “Sun bear populations could be blinking out in many small forest patches unbeknownst to us,” Dave Garshelis, co-chair of the specialist group, says. “We need this information to highlight where direct conservation actions should be focused.”

Cover image of the Smithsonian Magazine April/May 2024 issue

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Alex Fox

Alex Fox | | READ MORE

Alex Fox is a freelance science journalist based in California. He has written for the  New York Times, National Geographic,  Science ,  Nature and other outlets . You can find him at .

Sebastian Kennerknecht | READ MORE

Sebastian Kennerknecht is a wildlife and conservation photographer visually covering wildlife and environmental issues internationally.

Watch CBS News

How this year's warm, dry winter has affected Minnesota's bear population

By Erin Hassanzadeh

Updated on: March 25, 2024 / 10:28 PM CDT / CBS Minnesota

MINNEAPOLIS —   Two years ago, WCCO took you inside a Minnesota bear den  in the Chippewa National Forest near Grand Rapids.

At the time, Minnesota Department of Natural Resources biologists were worried because drought had hit the food supply hard. That season was one of the worst years for food since the 80s, when the DNR started research to manage the state's black bear population. That meant some bears, like the one we followed, didn't have cubs as expected.

This year, DNR biologists went back out to see how bears are faring in what's been an unusual winter .

February in the Brainerd area had an unusual crunch to it with all the dried leaves on the ground and no snow — not exactly textbook hibernating weather.

When bears tuck into their dens for the winter, Dr. Andy Tri gets to work, taking his tool that communicates with the collared trackers on the bears the state is monitoring to locate them in their dens. 

READ MORE:  2023 was the planet's hottest year on record, and climate-related disaster costs are mounting

Tri and his partner at the DNR traverse the state, checking on dens to see how the bears are doing — snow or no snow.

In this excursion, we're expecting to find a mama bear and her yearling. The beeping of Tri's tracking device lets us know we are getting closer.

What we find here inside her den is pretty textbook.

"So this is BR23. She's a 4-year-old female," said Tri. "This is her very first little baby."

Except her little baby isn't so little at nearly 100 pounds, which is on the larger side for a yearling. That may seem surprising given our persistent drought.

"The oaks which are a primary food source for bears get real stressed," said Tri.

When it's dry, the oaks drop a lot of acorns — the perfect snack for a hungry bear. There was also a perfectly timed rain, creating a berry bounty.

"Everybody seems to be in really good shape. Cub survival is pretty darn high on the bears we've visited so far," said Tri.

We also wondered: Does a warm winter change their annual slumber?

"It doesn't really," said Tri. "The females are sticking in their den even with no snow on the ground."

Tri says it's still probably not worth it for the mama bears to come out early.

"You're going to lose more calories than you're going to gain," said Tri. "It's an energy conservation measure."

WCCO asked if snow depth matters, knowing it's a great insulator for bear dens.

"It doesn't seem to," said Tri. "There will be bears that den above ground even at 30 below. They're beyond extremely resilient."

In fact, it seems there isn't much that will rattle Minnesota black bears.

"In general, I think bears are going to be a climate change winner because they're just so adaptable, but the landscape moving forward is going to change dramatically," said Tri. 

READ MORE: How is Minnesota's unusually warm winter affecting the moose population?

Tri says trees and food are essential for the bears. Mature oak die-off is a concern, and tamarack tree loss too.

For now, most like Bear BR23, are doing just fine.

"The kids are alright," said Tri. "They're one of those charismatic species in Minnesota we're just lucky to have."

Tri says bears are emerging a little early from their dens this year. They usually leave in early to mid-April, but one-fourth of them are already starting to move around.

If you see a bear , do not approach or feed them, secure your trash and recycling bins, and once grilling season hits, be sure you clean and store them.

Some of you might be wondering about Bear 6080 — that's the mama WCCO first met in 2022. She didn't have any cubs that year,  but last year she had two. Both of them survived and are doing well.


Erin is back home in the Twin Cities after stops in South Korea and Omaha. The Jefferson High School grad (Go Jags!) is excited to get back to storytelling in the community that raised her.

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  • Bears stadium proposal has us asking: Who’s in charge of Chicago’s lakefront?

That the Bears can just diesel their way in, Bronko Nagurski-style, and attempt to set a sweeping agenda for the future of one of the world’s most iconic water frontages is more than a bit troubling.

An aerial view of Soldier Field and parkings lots to the south.

The area south of Soldier Field includes a parking lot and garage. The Bears are looking at that land as the potential site of a new lakefront domed stadium.

Brian Ernst/Sun-Times

Chicago's Near South lakefront is one of the crown jewels of the city, with its parkland, lake access, harbor and three world-renowned museums, all within a few blocks of each other.

And it deserves better treatment. Consider this:

On the southern end near 23rd Street, McCormick Place's Lakeside Center threatens to rot in place.

Then there is Northerly Island Park, with all of its potential wasted by a split-personality redevelopment that put a 30,000-seat live event pavilion on its north side, but a nature sanctuary on its south.

Now come the Chicago Bears with plans to shoehorn a giant domed stadium — and maybe even hotels and a sports museum — on the parking lots just south of their current Soldier Field playground.

This editorial board has expressed concerns about the current proposed Bears stadium ( we don’t like it ) and certainly will again as the team's plans develop.

Still, in a way, you can't (yet) fault the Bears for trying. They are a for-profit organization, looking for a stadium deal that makes them even more money.

But that the team can just diesel their way in — Bronko Nagurski-style — and attempt to set the agenda for a critical section of one of the most iconic water frontages in the world is more than a bit troubling.

  • Bears president Kevin Warren touts benefit of downtown stadium
  • Ask voters about taxpayer subsidies for Bears, Sox stadiums, former Gov. Quinn says

It points to an even larger question: Who in government is truly minding the store when it comes to mapping the future of this critical area of Chicago's lakefront?

It isn't as if the tools aren't there. Chiefly there is the 51-year-old Lakefront Protection ordinance that keeps private development off the city's shores and can give the thumbs up or down to public development that violates the long-held and fought-for concept of the lakefront as a public trust.

And there's the Chicago Park District, an independent governmental body — on paper, at least — which can set the agenda for the lakefront. Then there's the mayor, through which all big things must (or should) pass.

Advocates such as Friends of the Parks are in the mix too, with the ability to sue to stop projects and policies that might negatively impact the lakefront.

Public land, free for development?

So what's the problem? For too long, Chicago's parks and lakefront have been looked at as easily developable land, rather than sacrosanct public places that act as respite from the hurly-burly of the big city.

Until that changes, lakefront and park space will always be under the threat of some sort of attack.

At least on the museum campus, the institutions themselves are doing their part to improve the area. For example, the Shedd Aquarium is pouring $500 million into creating new galleries and programs between now and 2027.

The Adler has spent millions in recent years restoring the dome on that marvelous Art Deco facility .

"I think the area at the museum campus is the most beautiful piece of property in the country," Bears CEO Kevin Warren told The Athletic this week.

He is absolutely right.

But Warren is wrong when he says "We’ll be able to build a campus together with the museums, with the stadium, with the lake, with the downtown on the backdrop, and to be able to enjoy Chicago like we should be able to enjoy Chicago."

One of these things doesn't belong here, as they used to sing years ago on that public television children's tv show. For the lakefront, that thing is another professional football stadium and all that would come with it.

While Soldier Field has been in Burnham Park since 1924, it was originally built as a properly-scaled lakefront public gathering space for big events: Boxing, major religious gatherings, sporting events, and the like.

The notion of a new domed stadium and hotels goes against all that, even if the Bears kept their promise of spending $2 billion to build the place, then gift it to the public.

Still, the museum campus, Soldier Field, Lakeside Center and Northerly Island need help and a vision for the future.

While we're at it, we are intrigued by former Gov. Pat Quinn's call this week for an advisory referendum on the November ballot asking voters to weigh in on whether the Bears or Sox should receive public subsidies to build new stadiums.

But a non-binding ballot question on this is pretty much a time-waster. What's needed more than a referendum is clear-eyed leadership from the mayor, the governor and those elected to look out for the best interests of the public, rather than billion-dollar sports franchises.

Same for the Near South lakefront. The public and Burnham Park would be better served by the public, government and civic leadership working together to determine the area's future.

The Sun-Times welcomes letters to the editor and op-eds.  See our guidelines .

Bears considering lakefront for new stadium

  • Despite $1B cost, mayor open to helping develop area around proposed new Bears stadium on lakefront
  • Bears president: Lakefront stadium gives team ‘best opportunity for success’
  • New Bears lakefront stadium could come with hotel, sports museum — and $1B campus revamp
  • Bears urged to consider Michael Reese hospital site for domed stadium to avoid lakefront legal battle
  • Bears would put $2B in private money into publicly owned lakefront stadium under new push
  • Bears should think big on lakefront domed stadium, state lawmaker says
  • White Sox, Bears discussing ‘financing partnership’ for two stadiums, developer says
  • Could Bears stay on lakefront? Team researching Soldier Field parking lot for new stadium

Proposed Arlington Heights stadium updates

  • Arlington Heights proposes tax deal for Bears stadium
  • Bears ‘disappointed’ after Board of Review blocks lower Arlington Heights property tax bill
  • Cook County officials touch down on $124.7M assessment on Bears’ proposed stadium site in Arlington Heights
  • Bears and suburban school districts are $100 million apart on value of Arlington Park

Columns and editorials

  • Chicago’s lakefront is too important to just hand-off for a new Bears stadium
  • Lawmakers, get ready for the double-team from White Sox, Bears for stadium money
  • Rick Morrissey: The Bears and the White Sox with a hand out together? Be very frightened.


Fox Weather App on an iPhone, Fox Weather logo overlapping

4 bear cubs take time to 'paws' and reflect during lazy afternoon on water at England safari park

Keepers said they were delighted to see the four younger cubs, named harvard, maple, colorado and aspen, named for their north american origins in the wild, head right over to the swan boat to "investigate" their new friend.

A video shared by the Woburn Safari Park in England showed four bear cubs enjoying an afternoon on the water after a small lake formed after recent heavy rain.

Watch: Bears enjoy afternoon on the water at Woburn Safari Park in England

A video shared by the Woburn Safari Park in England showed four bear cubs enjoying an afternoon on the water after a small lake formed after recent heavy rain.

RIDGMONT, England – A sloth of North American black bears was recently treated to a relaxing afternoon on the water at the Woburn Safari Park in England after recent heavy rain created a small lake within their enclosure.

So, please. Bear with us. You’re about to read some em bear issing bear puns.


This image provided by the Woburn Safari Park in England shows a North American black bear taking in the views from a swan paddle boat on a small lake that formed after recent rain.

This image provided by the Woburn Safari Park in England shows a North American black bear taking in the views from a swan paddle boat on a small lake that formed after recent rain.

(Woburn Safari Park)

Staff came up with the idea to keep the bears entertained after the lake formed and noticed one of the park’s swan boats was waiting for new pedals.

"So, we had the idea of turning this into interesting enrichment for them," said Tommy Babington, Deputy Head of the carnivores section of the park.

The swan boat was then placed on the lake with the hopes that the bears would find the new addition bear y interesting.


This image provided by the Woburn Safari Park in England shows a North American black bear climbing onto a swan paddle boat on a small lake that formed in the park after recent rain.

This image provided by the Woburn Safari Park in England shows a North American black bear climbing onto a swan paddle boat on a small lake that formed in the park after recent rain.

Keepers said they were delighted to see the four younger cubs, named Harvard, Maple, Colorado and Aspen, named for their North American origins in the wild, head right over to the swan boat.

Babington said the bears were "immediately intrigued" and "wasted no time in investigating the swan paddle boat."

Woburn Safari Park shared photos and videos of the bears discovering their new friend on the water and showed them taking some time to take in the sights and paws and reflect on their short lives so far.


This image provided by the Woburn Safari Park in England shows a sloth of North American black bears on a swan peddle boat on a small lake that formed in the park after recent rain.

This image provided by the Woburn Safari Park in England shows a sloth of North American black bears on a swan peddle boat on a small lake that formed in the park after recent rain.

One of the photos shows a cub getting comfortable on the boat with bearly any room for its brothers and sisters.

"It was great fun for visitors to see them climb on board," Babington said. "We love devising new ways to provide food, scent and habitat enrichment that stimulates their natural foraging behaviors."

The park says the young sibling black bears, two males and two females, spend a lot of time foraging, play fighting, eating and sleeping.


This image provided by the Woburn Safari Park in England shows a sloth of North American black bears on a swan paddle boat on a small lake that formed in the park after recent rain.

This image provided by the Woburn Safari Park in England shows a sloth of North American black bears on a swan paddle boat on a small lake that formed in the park after recent rain.

The park said that bears are naturally very curious animals, and keepers will encourage that behavior with different kinds of activities for them to help keep their minds and bodies active.

While it may be a "less conventional approach" to keeping them stimulated, the park said "it certainly was a hit."

And the story of the bears is quickly going viral after the park shared a video of the bears enjoying their time at the newly formed lake on TikTok .

  • International

March 28, 2024 - Baltimore Key Bridge collapse

By Antoinette Radford, Maureen Chowdhury , Tori B. Powell , Elise Hammond and Aditi Sangal , CNN

Our live coverage has ended. Follow the latest news on the Baltimore bridge collapse or read through the updates below. 

Here's what we learned from the authorities this evening

From CNN staff

The sun sets on the Francis Scott Key Bridge on Thursday, March 28.

The federal government has given Maryland officials the $60 million requested to cover the first steps of responding to  the collapse of the Francis Scott Key Bridge , according to a Federal Highway Administration news release.

Federal Highway Administration chief Shailen Bhatt said the emergency funding would go toward removing debris, rerouting traffic and ultimately rebuilding the bridge.

Here's what else the authorities said in a news briefing this evening:

  • Four directives to recovery: Gov. Wes Moore outlined four main priorities as Maryland looks to recover after the bridge collapse. The directives include: Continued focus on efforts to recover the construction workers presumed dead "to bring a sense of closure to these families," open the channel and restart traffic to the port, taking care of those affected, rebuilding the Key Bridge.
  • Murky water conditions: Moore said the " water is so dark , and debris is so dense, that in most instances our divers cannot see more than a foot or two in front of them."
  • Major resources mobilized: The Army Corps of Engineers is moving the largest crane in the Eastern Seaboard to Baltimore to help clear the channel, and it is expect to arrive later on Thursday evening, Maryland Gov. Wes Moore said. Clearing the channel has been an important goal so trade and traffic through the port can resume. The Army Corps of Engineers plan to cover the full cost of clearing the channel where Baltimore's Key Bridge collapsed, Sen. Chris Van Hollen said Thursday.
  • One larger vehicle detected underwater: There's at least one vehicle of a large size that has been detected underwater, and it is encapsulated by the superstructure of the bridge, concrete and other things, according to Col. Roland L. Butler Jr., the superintendent of Maryland State Police.
  • Monitoring possible leaks and pollution: Over 2,400 feet of boom have been deployed to contain any leaks of pollution in the aftermath of the collapse of the Key Bridge, Moore said. Separately, 14 containers on the ship were impacted , and they contained items like soap and perfume, Coast Guard Rear Adm. Shannon Gilreath said, adding that he did not have information on whether any of those materials went overboard. Air monitors are in place to track any potential threats and they have not picked up any threats so far, Gilreath said.

There's at least 1 larger vehicle underwater, official says

From CNN's Aditi Sangal

There's at least one vehicle of a large size that has been detected underwater, according to Col. Roland L. Butler Jr., the superintendent of Maryland State Police.

"There's at least one vehicle, larger in size, that is completely encapsulated by the superstructure of the bridge, concrete," among other things, Butler said Thursday evening. "It's going to take some time to get to that, and it's going to take some time to do that carefully" before divers can go to recover that vehicle, he added.

2,400 feet of boom was used to contain possible toxic materials, Maryland governor says

Wreckage lies across the deck of the Dali cargo vessel in Baltimore on Wednesday.

There have been over 2,400 feet of boom deployed to contain any leaks of pollution in the aftermath of the collapse of the Key Bridge, Maryland Gov. Wes Moore said Thursday.

He said he personally did not see any sheen on the water when he went to assess the situation on site.

Remember: 56 containers with hazardous materials were found on the vessel.

There are 14 containers on the ship were impacted, and they contained items like soap and perfume, Coast Guard Rear Adm. Shannon Gilreath said at the briefing, adding that he did not have information on whether any of those materials went overboard.

Air monitors are in place to track any potential threats and they have not picked up any threats so far, Gilreath added.

Baltimore mayor says he remains hopeful bodies of other workers will be recovered

From CNN's Elise Hammond

Baltimore's mayor said he is still "hopeful" the bodies of the other workers presumed dead will be recovered.

Authorities announced on Wednesday they were pausing search and recovery efforts  for the four other workers presumed dead because debris made it unsafe for divers to continue. Once this next phase of salvage operations is complete and the debris is cleared, divers will search for more remains.

Baltimore Mayor Brandon Scott said that during the salvage operation, he hopes "we are able to recover those who remain missing and bring them home to their families.

The mayor said he directed his administration to work with the governor’s office “on any and every effort that must be taken.”

Army Corps of Engineers will bear the full cost of clearing the channel, Sen. Chris Van Hollen says

Maryland Sen. Chris Van Hollen speaks at a press conference Thursday.

The Army Corps of Engineers will cover the full cost of clearing the channel where Baltimore's Key Bridge collapsed, Maryland Sen. Chris Van Hollen said Thursday.

"We all recognize that getting the Port of Baltimore running again at full speed is a priority given all the jobs that are associated with it, all the small businesses, all the other businesses," Sen. Van Hollen said at Thursday's news briefing. "And as the governor pointed out, this is not just a Maryland issue, it's a national and global question."

The largest crane in the Eastern Seaboard is expected to arrive in Baltimore later today, governor says

The Army Corps of Engineers is moving the largest crane in the Eastern Seaboard to Baltimore to help clear the channel, and it is expected to arrive Thursday evening, Maryland Gov. Wes Moore said.

"Under the leadership of Col. (Estee S.) Pinchasin, the Army Corps is moving the largest crane in the Eastern Seaboard to Baltimore to help us," Moore said at a news conference. "It is estimated that will arrive later this evening."

"It's a 1,000-ton crane coming around midnight," Sen. Chris Van Hollen said at the same news conference. "And another 400-ton crane coming Saturday for the operations to clear the channel."

The post was updated with information about the crane from Sen. Van Hollen.

Officials are assessing pieces of the bridge before they pull them out of the water, Coast Guard says

Coast Guard Rear Adm. Shannon Gilreath speaks at a press conference Thursday.

Officials working to remove the collapsed Key Bridge from the channel are conducting a full assessment of all pieces of debris before they can lift them out of the water, Coast Guard Rear Adm. Shannon Gilreath.

This assessment is critical in figuring out how to cut the bridge into the right size pieces so cranes can lift them out, he said.

“We are doing those assessments right now with underwater surveys, with engineering teams back in unified command,” Gilreath said, adding that the assessment is in coordination with several other partners, including the US Army Corp of Engineers.

“That is our number one priority is to reopen the Port of Baltimore as fast as we can, and do it safely,” he added.

Murky conditions are hindering divers' vision during underwater operations, Maryland governor says 

Water conditions are hindering divers' visibility as they conduct recovery operations, Maryland Gov. Wes Moore said Thursday.

"That water is so dark, and debris is so dense, that in most instances our divers cannot see more than a foot or two in front of them," Moore said at a news briefing. "So much of the operation is simply feel."

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PFAS decorative hero image

They’re in the air we breathe, the water we drink, the food we eat and the soil where that food was grown.

They’re in our carpets, our cookware, our drinking straws, our cosmetics and our clothes.

They’re in medical products, mining chemicals, clean-energy technology and the equipment that manufactures our computer chips.

Finding Forever Chemicals Wherever They’re Hiding

Nist scientists are helping reveal tiny amounts of ‘forever chemicals’ in our food, water, clothing and environment..

They’re called per- and polyfluoroalkyl substances, or PFAS, a group of thousands of compounds that contain a chemical bond between fluorine and carbon. That bond has proved to be one of the most stable and unbreakable known to chemistry — a fact baked into the common nickname “forever chemicals,” because once PFAS are created, they last a very long time.

First manufactured in the 1940s, PFAS have seeped into our daily lives, and our bodies. In recent years, they have emerged as a serious public health concern. Scientists have reported evidence that certain PFAS, at high enough concentrations, may harm health by suppressing the immune system or causing cancers , obesity , thyroid problems and birth defects . 

Forever chemicals have also been found in remote forests, in the Arctic and at the bottom of the ocean. Reminiscent of pesticides like DDT in the 1960s and PCBs in the 1970s, they’ve emerged as some of the most pervasive and troublesome environmental contaminants of our time.

At the same time, health researchers are still determining how harmful PFAS are at the levels most of us are exposed to. And some of the studies that have raised the most alarms have used measurement methods that can overestimate the chemicals’ concentrations.

Researchers and regulators now face a daunting task: They must accurately measure PFAS in the countless places they’ve ended up and assess when and where these compounds have reached dangerous levels. To do so, scientists must often measure the chemicals at extremely low concentrations. PFAS can be found in food, drinking water and other materials in concentrations of parts per billion or even parts per trillion — equivalent to a few drops in an Olympic-size swimming pool.

This is where the National Institute of Standards and Technology (NIST) comes in. NIST scientists have pioneered methods that have made laboratory tests for PFAS in food, water, soil, firefighter gear and other materials more accurate. NIST research will support laboratory tests needed to implement the nation’s first-ever PFAS drinking water regulations , which the Environmental Protection Agency (EPA) is currently developing.  

NIST researchers have also produced one of the world’s largest public databases of empirically measured PFAS masses, to help other researchers and labs more efficiently sniff out these troublesome compounds.

PFAS represent the kind of measurement challenge that NIST was made to tackle.

“In the federal government space, NIST was ahead of the game on PFAS,” says NIST research chemist Jessica Reiner.

A Useful but Troublesome Chemistry

The PFAS industry started in the late 1930s and early 1940s, after an engineer at the company DuPont invented a fluoropolymer that became known as PTFE. Marketed as Teflon, PTFE became a blockbuster, launching a multibillion-dollar industry of nonstick coatings applied to cookware and an almost unlimited range of other products. 

Over the ensuing decades, thousands of PFAS were manufactured and incorporated into industrial lubricants, water-repellent clothing and carpeting, food packaging and more. If you’ve ever marveled how the wrapper around a greasy fast-food burger keeps your hands clean, or how effortlessly your lightweight rain jacket sheds water, you can probably thank a PFAS.

“Chemically they’re amazing — they do amazing things,” says John Kucklick, leader of the Biochemical and Exposure Science Group at NIST. “Anything that repels grease is probably fluorinated.”

Illustration of molecule includes yellow, blue and purple balls representing atoms.

The chain of carbon atoms (yellow balls) and fluorine atoms (blue balls) characteristic of PFAS molecules is uniquely good at repelling water and grease.

Chemical companies had evidence of PFAS-related health impacts as early as the 1950s. But only in the late 1990s and early 2000s did government agencies such as the EPA take a hard look at the chemicals, after a lawsuit exposed DuPont-led studies of their harmful effects on factory workers. Around that time, researchers at Michigan State University found PFOS , a major PFAS of concern, in the tissues of fish, birds and mammals throughout Europe and North America, including the Arctic. “That really lit the fuse for all this PFAS research,” says Kucklick. “It became a very hot topic.”

PFAS had proliferated far faster than scientists were able to study each one in detail, creating an urgent need to accurately measure the compounds in all kinds of contexts. Among the first things NIST scientists did was test for PFAS in the tissues of animals kept in the institute’s biorepository , based in Charleston, South Carolina. The repository contains frozen tissue from marine mammals and sea turtles that were collected starting in the 1980s. NIST researchers led by biologist Jennifer Lynch found PFOS and other PFAS in sea turtle blood and marine mammal livers — a concerning result that was consistent with other published studies. 

There were also more encouraging findings. Lynch’s liver measurements revealed that manufacturers’ voluntary phase-outs of certain PFAS starting in the early 2000s had, over time, reduced the levels accumulating in animals.

Reiner kick-started another PFAS-related research program when she joined NIST in 2008. She had studied with the author of the influential animal contamination study and done a postdoc at  the EPA. But after a 2004 paper by an international group of researchers detailed how PFAS measurements could go awry — and suggested that NIST could provide standards — Reiner “realized we had a lot of measurement problems” to solve. At the time, different labs' estimates of PFAS concentrations in the same material deviated by as much as several hundred percent. This made the measurements hard to trust. “It was the wild west,” says Reiner.

In the federal government space, NIST was ahead of the game on PFAS.” —Jessica Reiner, NIST research chemist 

One problem involved compounds that can mimic PFAS in a lab test, leading to errors. Eggs, for example, contain a bile acid that can easily be mistaken for certain PFAS. In a particularly high-profile case, when a scientist with the Food and Drug Administration presented a preliminary finding of high PFAS levels in chocolate cake, the report ignited a media firestorm. “That chocolate cake won’t last forever, but the chemicals in it might,” one headline stated. Follow-up testing by the FDA soon revealed the finding to be a false positive ; the cake contained no detectable PFAS. 

Building on Lynch’s research, Reiner first worked on measuring PFAS accurately in existing NIST reference materials, including human plasma, fish and house dust. These are well-characterized materials that any lab can purchase and measure with its own equipment. If the lab's measurement differs from the NIST-provided value on the label, its equipment needs to be adjusted or calibrated. NIST reference materials have helped make a wide range of important health and environment-related tests more accurate and reliable.

By 2012, Reiner’s team had produced new standard reference materials, or SRMs, for several of the PFAS most commonly found in biological samples. Over several years, the amount that different labs’ PFAS measurements deviated from the average plummeted from several hundred percent to around 40%, indicating that lab testing had become reasonably reliable. Eventually, Reiner thought, “OK, we’re good [with PFAS]; let’s move on.” She started working on flame retardants and plasticizers.

NIST’s PFAS-Related Standard Reference Materials

NIST Researchers Develop Standards to Help Eliminate ‘Forever Chemicals’ in Firefighting Foams

NIST Releases Great Lakes Sediment Material for Measuring Organic Pollutants

But events soon brought her back to PFAS. In 2016, New York State detected PFOA , another common PFAS, in the Village of Hoosick Falls’ public drinking water supply and Town of Hoosick private drinking water wells above the EPA health advisory level of 70 parts per trillion (ppt). PFOA, though no longer produced in the U.S., had been widely used to make products such as Teflon and foams for fighting fires. It has been linked to elevated cholesterol, thyroid disease, reduced immune response and some forms of cancer. Other studies soon found PFOA and other PFAS in drinking water systems around the country. 

It turned out that Reiner’s — and NIST’s — work on PFAS was just beginning.

Illustration shows how PFAS from landfills, manufacturing and firefighting foams can contaminate groundwater, agriculture, drinking water and oceans.

Because PFAS don’t break down, they have been able to move widely through the environment, contaminating everything from food to drinking water to marine wildlife.

It’s in the Water

While PFAS is everywhere, it’s made the largest public splash, so to speak, in water. Since the 2016 finding of PFOA in New York, PFAS that leaked or discharged from factories, military bases and other facilities have been found in 45% of the nation’s tap water, according to the U.S. Geological Survey. More than 20 states have since moved toward regulating the chemicals. In March 2023, the Environmental Protection Agency proposed the first national limits for six PFAS in drinking water . The EPA proposed regulating concentrations of PFOA and PFOS, for example, at 4 parts per trillion.

To give regulated entities and broader society confidence, government and private labs will need to accurately quantify PFAS even at very low concentrations. That will require recognizing and controlling for issues that can mess up test results, says NIST research chemist Alix Rodowa. “PFAS are in so many things!” she says. “They’re in the instrumentation we use. Do we have Teflon tape on things? Is it in the materials we’re using to collect the samples? We have to think about all those things, especially at those ultra-trace levels.”

Alix Rodowa wears safety glasses and gloves in the lab as she reaches for a container of clear liquid on top of a piece of scientific equipment.

Alix Rodowa in the lab figuring out how to accurately measure PFAS in drinking water.

Rodowa and her colleagues have upgraded their measurement equipment with PFAS-free tubing and developed a suite of “tricks” to reduce contamination. She has been working on an SRM that labs can use to ensure their drinking water tests are accurate. Initially she was considering sending labs bottled water with a known amount of PFAS. But she realized the chemicals were sticking to the sides of the bottle, potentially compromising the analysis results. 

So she switched to a two-pronged approach: ship out a standardized volume of tap water purified using reverse osmosis — among the most effective PFAS filtration methods available — along with an ampule of PFAS diluted in methanol to a known concentration. Methanol reduces intermolecular forces that cause the PFAS to stick to the bottle, allowing for a more uniform mixture of PFAS and water. Lab workers who purchase the SRM can pour the solution into the purified water and test it on their equipment. 

The next step is to send the samples to labs to get feedback, which will help Rodowa further refine the material. Only when labs can consistently use the product to improve test results will NIST add it to its catalog of reference materials. The final product is still at least a year away — "SRMs are really hard to make,” Rodowa says — but when it comes out, “it will absolutely help. It will make the results much more comparable over time and build confidence for consumers of the commercial lab reports.”

The work could especially aid new labs coming online to meet the enormous and growing need for water testing, adds Reiner. “If they have a material like this to help them develop their method and get it set up correctly, they’re going to end up saving a lot of money and a lot of time.”

Fluorinated Food Fears

Few things are more frightening than the thought that the food you eat or feed to your family could contain harmful chemicals. And even if the FDA’s initial chocolate cake report proved a false alarm, PFAS has been showing up in food with distressing regularity. 

NIST’s food-related PFAS work began with Reiner’s studies of fish from the Great Lakes that the institute had already used to make reference materials for other chemical contaminants. But the urgent need for additional PFAS-specific materials became clear a few years ago, when a dairy farmer in Maine discovered the chemicals in high concentrations in his cows, likely because they drank contaminated groundwater or ate contaminated feed. The farmer ended up making the heartbreaking decision to cull his herd. But there was a silver lining — through connections at the FDA and Maine’s public health department, NIST chemists Benjamin Place and Melissa Phillips bought around 135 kilograms (300 pounds) of meat from the farmer. 

The meat arrived in the form of frozen patties. But figuring out how to accurately measure concentrations of PFAS in such a complicated material was far from trivial. The patties were first sent to the Hollings Marine Lab in Charleston, South Carolina, where they were chilled to extremely low temperatures and milled into a powder. Then, Place and his colleagues had to solve various challenges, like preventing the pinkish-red, slurried meat from sticking to lab equipment and test tubes. The process has proved to be one of the more, shall we say, visceral ones NIST researchers have encountered. 

Two photos side by side: Melissa Phillips, wearing safety glasses, poses leaning over an open chest freezer, holding a plastic bag of spinach. Ben Place, in a white lab coat and gloves, is holding up a frozen container in a laboratory.

NIST’s Melissa Phillips holds a bag of frozen spinach, while Ben Place holds a vial of frozen ground meat. Both are destined for future SRMs that will help labs accurately measure PFAS in food.

Place and Rodowa are now working to create SRMs for cow and pig meat. Rodowa and Place have also started preparing an SRM based on PFAS-contaminated spinach. And they have plans in the works for animal feed based on fermented corn stalks, which are currently stored in a NIST freezer.

With more and more states discovering PFAS-contaminated food and developing regulations around the chemicals, demand for these products is likely to be high. Already, NIST’s 15 PFAS-related SRMs have become some of the agency’s most popular products. Sales of the Great Lakes fish SRMs doubled between 2019 and 2021; the materials sometimes sell out. “They’ve been flying off the shelves,” says NIST research chemist Kate Rimmer.

Firefighters in the Spotlight

Chemicals in water and food affect everyone. But certain groups are far more likely than the rest of us to be exposed to high levels of PFAS. 

One of those groups includes the people who protect us and our homes from fire. Firefighters have raised alarms as studies have found elevated PFAS levels in their blood compared with the general population, along with higher rates of certain cancers .  

While firefighters could be exposed to PFAS from multiple sources, turnout gear — the familiar yellow and tan outfits firefighters don before plunging into a burning building — has become a prime suspect, thanks in part to university studies that have garnered media attention. This gear must meet stringent requirements for flame retardance and water repellence. And one of the most reliable ways for manufacturers to meet the performance standards is to use PFAS.

The graphic says "PFAS in Firefighter Gear" and depicts a firefighter wearing protective turnout gear with a diagram of the three layers of the gear, which are the outer shell, the moisture barrier and thermal barrier.

A firefighter’s protective "turnout gear" is composed of three distinct layers made of different textiles. In response to concerns about the gear possibly exposing firefighters to PFAS — several of which have been linked to cancer — NIST researchers investigated the presence of the chemicals in textiles used to make the layers.

In 2020, a bill sponsored by Sen. Jeanne Shaheen of New Hampshire directed NIST to identify and quantify the PFAS in turnout gear. 

The congressional funding enabled the research team to buy dozens of PFAS standards — commercially available solutions with precisely calibrated concentrations of the PFAS of interest — to calibrate its equipment. Each standard can run thousands of dollars. The researchers ultimately analyzed 53 compounds and 20 pieces of brand-new turnout gear — the most comprehensive examination published to date. 

Due to the high cost of buying all the gear and chemical standards and the amount of work involved, “I do not think this study could have been done by anybody else other than the federal government,” says Rick Davis, the NIST materials research engineer who led the research.

The team’s first report , released in May 2023, bore both good and troubling news. On the concerning side, all the fabrics contained some PFAS. The moisture barriers — the middle layer firefighters wear — and the outer shells the researchers tested contained the highest concentrations of the chemicals, up to around one part per million. Davis says the chemicals are likely added to make turnout gear waterproof, and that gear manufacturers may be able to achieve similar performance levels without using PFAS.

I do not think this study could have been done by anybody else other than the federal government.” —Rick Davis, NIST materials research engineer

More positively, the thermal liners firefighters wear against their skin contained much less PFAS. Moreover, the chemicals found in high concentrations in the other layers were not PFOA and PFOS — the so-called long-chain PFAS that have been most intensively studied but also largely phased out — but rather chemicals with shorter carbon chains. Such short-chain PFAS are more quickly flushed from the body, though it’s not clear whether that makes them safer. 

A second study released in January 2024 examined gear that had been heated, abraded or weathered — the kinds of wear expected when battling a fire. The team found that abrasion caused the greatest increase of PFAS in all fabric types, whereas heating increased PFAS concentrations substantially in the outer shells and slightly in the thermal liners, while decreasing them in the moisture barriers. Weathered outer shells also showed a large increase in PFAS.  

On the other hand, when gear was laundered, PFAS concentrations declined slightly — though the released chemicals probably ended up in the wastewater stream, raising potential concerns about environmental contamination.

NIST Reports on Firefighter Gear

Researchers Pin Down PFAS Prevalence in Firefighter Gear

Wear and Tear May Cause Firefighter Gear to Release More ‘Forever Chemicals’

Davis stresses that his team’s results do not address whether firefighters’ gear is harming them. “These studies better define the PFAS a firefighter could be exposed to from their gear,” he says, “which gives a narrower PFAS focus for those who will conduct firefighter health exposure studies.” Researchers at universities and other agencies are just starting to examine the health impacts of short-chain PFAS; one major unknown is how readily they move from clothing into the wearer’s body. The NIST studies aim to provide a rigorous and unbiased foundation for future decisions around firefighting gear. 

And the work is far from done. Davis’s next project will look at PFAS in firefighter gloves, hoods and other gear. Another future study will examine PFAS at fire stations and other workplace exposures. 

Another way firefighters could be exposed to PFAS is through aqueous firefighting foams. Starting in the 1960s, these products were used to quench flaming liquids like gasoline at sites such as military bases, oil refineries, airports and chemical factories. PFAS-based surfactants in these foams, which have proved uniquely good at smothering intense, high-temperature fires, can constitute up to 6% of the product’s total weight — an extremely high concentration found virtually nowhere else. During military training exercises, the chemicals often ended up in concrete pits and, from there, leaked into nearby groundwater. In some cases, water contaminated a half-century ago still appears foamy.

Congress has ordered the Department of Defense — the top user of these foams — to phase out most PFAS-containing firefighting foams by 2024. But legacy foams that remain on bases and other facilities could continue to contaminate the environment. To help ensure the fire suppressants people are using are PFAS-free, Reiner and other NIST researchers worked to develop SRMs for foams. The project was challenging, Reiner says, because the foam created when these products are used turned out to have a higher PFAS concentration than the overall product, so if a lab measures just the foam, it will get too high a value. 

In September, the team announced four new SRMs with formulations of PFAS found in several major types of firefighting foams. Labs around the country can use these materials to calibrate the equipment they use to analyze foams for PFAS, Reiner says. 

Four small dark glass ampules stand on a lab table, marked with skull and crossbones danger icons.

A series of reference materials contain precise measurements of per- and polyfluoroalkyl substances (PFAS), known as forever chemicals, in firefighting foams. These foams, called aqueous film-forming foams (AFFFs), are used to suppress fuel fires. Analytical labs can use the reference materials for measuring PFAS in the foams so they can be removed.

A Measurement and Mitigation Challenge

Like them or not, PFAS are part of our world — and not all are necessarily acutely dangerous. Fluorinated polymers used to lubricate surfaces and prevent abrasion, for example, are relatively stable and seem to present less urgent health or environmental risks than more mobile compounds like PFOA and PFOS. Such polymers appear in manufacturing equipment used for semiconductors and many clean-energy technologies, highlighting their importance to the modern economy. A push to purge them all would be costly. 

And in some cases, it may be that only PFAS can do the job. If gasoline ignites on a ship or in an airport, you probably want whatever will quench the flames most quickly, even if it contains PFAS.

On the other hand, some products that currently contain PFAS, such as carpets and food wrappers, may not need them. (Indeed, the FDA recently announced that food packaging containing PFAS would no longer be sold in the U.S. ) And reducing levels of the chemicals in food, water and the environment is a clear priority.

NIST’s forthcoming drinking water SRM “will make the results much more comparable over time and build confidence for consumers of the commercial lab reports.” —Alix Rodowa, NIST research chemist 

The challenge facing measurement scientists is to pinpoint the concentrations and situations in which PFAS is truly harmful — and to communicate that science effectively, so that the public is empowered and not just alarmed. The proliferation of PFAS — nearly 15,000 have been identified, according to the EPA — has made this an especially daunting challenge. 

One way NIST is helping is by creating a database of PFAS chemical structures and masses . Researchers with a sample they suspect might contain PFAS can run a process called mass spectrometry and check their results against the NIST database to look for a match. The database contains 132 structures, including many of the most commonly found PFAS compounds and fragments, making it one of the largest public databases of PFAS masses. And there are plans to add more, including by allowing outside researchers to add their own data. 

“We’re hoping that if we can do the hard part and identify those chemicals, others won’t have to,” says Jared Ragland, a NIST research biologist who is leading the database effort.

A second, newly created NIST-based list includes compounds such as the bile acid that can confound PFAS measurements. Within days of a paper about the dataset coming out, Rodowa says she had already received information about four additional PFAS-mimicking substances, highlighting the need for such a resource. She and Reiner, who developed the list along with colleagues at the EPA, FDA and several other institutions, hope it will help prevent reports of exaggerated PFAS concentrations or false positives — which Reiner says can sometimes cause more harm than the chemicals themselves.

By helping the world accurately identify and measure PFAS, NIST scientists aim to guide us toward a safer, cleaner and, hopefully, more empowered and less fearful future. “We need to give people the right information,” Reiner says, “so they can make more informed decisions.”

Learn More About NIST’s Work Tackling PFAS Measurement Challenges

Spotlight: Alix Rodowa and PFAS in Groundwater

Creating a PFAS-Contaminated Meat SRM: A Q&A With NIST Chemists Melissa Phillips and Ben Place

Addressing Measurement Challenges for Detecting Chemicals That Could Cause Cancer

New NIST Database of ‘Forever Chemicals’ Will Help Scientists Monitor Environmental Pollution

Learn More About How These Forever Chemicals Are Measured

How Do You Measure Forever Chemicals?  


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