Watch tardigrades take an adorable stroll on their stubby little legs

"Plump and ponderous." That's how the Rockefeller University in New York describes tardigrades, those microscopic animals that can survive freezing, radiation and even being fired from a gun. A new study isn't testing their invincibility, but it is investigating why and how the micro-animals walk and run. 

Known as "water bears," the charming animals have eight short legs and move a lot like insects. "Their dumpy plod, however, raises the question of why tardigrades evolved to walk at all," the university said in a statement last week.

A team of researchers filmed tardigrades walking across different surfaces. The footage of the chubby-looking animals is delightful, but it has a serious scientific purpose. "Tardigrades have a robust and clear way of moving -- they're not these clumsy things stumbling around in the desert or in leaf litter," said Jasmine Nirody, lead author of a study on tardigrade movement published in the journal PNAS on Tuesday.

The team found the tardigrades adjusted their gait as the substrate got softer, until they were moving in a bounding or galloping fashion. Nirody shared a GIF illustrating this as part of a Twitter thread on Monday. Nirody said the movement was similar to that of some rigid-bodied desert beetles.

There are still questions as to why these miniscule, soft critters ended up moving like insects that are so much larger than them. The researchers have some ideas -- they may have a common ancestor or there's an evolutionary advantage to being able walk this way.

Tardigrades are extremely hardy and adaptable to different environments, from water to land. Understanding their moves could help with advancing robot locomotion, especially for microscopic robots, soft robots and ones that need to navigate tight terrain.

The tardigrades in the study seemed to be active participants. Said Nirody, "We didn't force them to do anything. Sometimes they would be really chill and just want to stroll around the substrate. Other times, they'd see something they like and run towards it." 

You can understand why so many people are obsessed with these unusual creatures. They're fascinating, weirdly cute and they look like living croissants.