I just think they’re neat: Tardigrades

Have you ever wondered if there’s an organism that can survive in any condition? From the freezing cold of space or the deep sea, to above boiling temperatures or radiation over 1,000 times the lethal human dose, the tardigrade, more commonly called the water bear, is just that. 

German zoologist Johann August Ephraim Goeze first discovered tardigrades in 1773, and he nicknamed them “Kleiner Wasserbär,” or “little water bear,” after their bear-like appearance. As of 2024, scientists have discovered about 1,300 species of tardigrades.

Although they might resemble a bear, tardigrades are only 0.5 to 1.5 millimeters long, or about the size of a grain of sand. They have long, segmented bodies similar to insects or crustaceans and eight short legs with claws on the ends. They have no respiratory organs — they are open hemocoels —  meaning they can breathe by performing nutrient and gas exchange throughout their entire bodies.

While tardigrades most often live in water, they can survive in almost any environment. They do this by entering a “tun” state, almost like a hibernation, where the tardigrade dries out its body of 95% of its water and rolls its head and legs into a small ball. When they’re in this state, they grow a glass-like protective shell, their metabolism slows to about 0.01% of its original state and they can survive up to 30 years without eating, according to Live Science. They can survive for up to a century in the tun state, so if found in harsh conditions, they can survive as tuns until their environment improves.

What this means for humans

Scientists have found tardigrade fossils dating back to around 500 million years, meaning these creatures have survived multiple five major extinction events on Earth. So, humans have a lot to study from tardigrades.

For example, the tardigrade’s ability to dry itself out and survive has the possibility of allowing scientists to preserve organs needed for transplants for longer.

One area scientists have focused on is the tardigrade’s ability to withstand extreme radiation. When humans are exposed to radiation, it causes the DNA to break down, killing the cells.

Tardigrades contain a protein called Dsup, which protects them from energy rays. Multiple studies have found that while Dsup does not prevent the genes from breaking down, it provides enough protection for tardigrades to survive. The tardigrade can then repair its DNA at a rate much faster than humans, according to the New York Times.

Over 50% of cancer patients undergo radiation therapy as part of their treatment. However, it also causes severe side effects in many cases.

A February 2025 study by MIT, Brigham and Women’s Hospital and the University of Iowa looked into the possible implications of the tardigrades’ protein with cancer treatment. The team injected RNA from the protein into mice and found that it protected the cells from radiation-induced damage, seeing about 50% less breakage in double-stranded DNA caused by radiation. They also found that the effects remained limited to the injection site, meaning the radiation therapy could still work on the cancerous cells with the protein protecting the rest.

Scientists are hopeful an adaptation of this discovery might lead to more ways to reduce the risks and suffering of radiation therapy for cancer patients.

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