Tardigrades are a strange species. You can make them into glass by drying them, and then firing them from a gun. Once they are rehydrated, you will still be able to have a living creature. Scientists discovered last year that their outsides are not the only thing that is tough.
However, they are capable of being brutalized in a number of other ways. How do these tiny creatures move?
They are the only animal with soft bodies such as theirs that can walk and the smallest known animal with legs.
Tardigrade walking on a soft gel. (Nirody et al., PNAS, 2021)
Jasmine Nirody, Rockefeller University mechanical biologist, wrote on Twitter: "One of the coolest things and initially most surprising about tardigrades walking towards me was how... they were at it,"
"They walk in a steady manner and look remarkably similar to larger animals."
To analyze the gait and coordination of Hypsibius species tardigrades, Nirody and his colleagues walked with them. We are now able to enjoy the results.
A tardigrade walking on a stiffer gel. (Lisset Duran).
"We didn’t force them to do any thing. Nirody says that sometimes they'd be very relaxed and want to just walk around the substrate." "Other times they might see something they like, and they would run towards it."
The team used tardigrades to walk them on different surfaces. Despite being completely different sizes and made from different materials, they found that their stepping patterns are very similar to insects.
Tardigrade walks on a stiff gel, with visible claws. (Nirody et al., PNAS, 2021)
The little guys were also recorded by the team trying to walk on smooth glass (they didn’t get very far on it), as well as on gels with two different degrees of stiffness to see how they walked in each situation.
A tardigrade on glass that is apparently unhappy. (Nirody et al., PNAS, 2021)
The team wrote in a paper that they found that tardigrades adjust their locomotion to a "galloping" coordination pattern when walking on soft substrates.
This strategy was also observed in arthropods, which can move well on flowing substrates or granular ones.
It is not clear why tardigrades move so similar to insects. Researchers aren't certain if there is a common ancestor with insects or if the walking ability evolved in two separate organisms.
The research was published in PNAS.
