Quirks and Quarks

How watching water bears walk could help us make small and squishy robots

Usually, soft microscopic animals like the tardigrade don’t walk - they roll, or swim, or slither. In a new study, researchers are trying to understand more about the way these animals move.

Tardigrades, also known as water bears, are the smallest legged animals on Earth.

A 3D rendered illustration of a tardigrade. These micro animals are unusual in the animal kingdom, partly because they walk along on eight legs instead of swimming or slithering like other animals of their size. (3Dstock / Shutterstock)

Researchers studying the tardigrade have figured out how this small, soft micro-animal walks, even though it defies all expectations by doing so.

Tardigrades, also known as water bears, have been around since the time of the dinosaurs, and can be found in every ecosystem on earth. Even though they're less than a millimetre in size, the tardigrade is incredibly resilient, easily surviving extreme conditions like being boiled in acid, or shot into the vacuum of space.

Another unique aspect of the tardigrade is the fact that they can walk. Typically, tiny animals like the tardigrade don't have legs, and don't walk at all — they slither, or swim. Tardigrades are also soft-bodied, lacking a shell like an insect, or bones like mammals, which are often required to propel appendages like legs. And yet, tardigrades have eight legs, and they use them to walk around, the smallest animals to do so.

"So essentially, it's like trying to pole vault with a noodle," researcher Jasmine Nirody told Quirks & Quarks host Bob McDonald.

Researcher Jasmine Nirody filmed hours of tardigrades walking, and discovered they stepped just like insects 500,000 times their size. (Lisset Duran/Jasmine Nirody)

Nirody wanted to look at how something so small and soft could walk, and how they walked. She and her team recorded hours of tardigrades walking along a special gel in a petri dish, and they found that they walk in a manner similar to that of insects 500,000 times their size. This could help solve evolutionary questions about tardigrades, as well as help inform new ways of building soft robotics.

The research was published in the journal PNAS.

Jasmine Nirody is an Independent Fellow joint between The University of Oxford and Rockefeller University in New York. You can listen to her full interview with Bob McDonald at the link above.


Produced and written by Amanda Buckiewicz