A walk around the block as a starfish

You may never have paused to think about how a sea star moves about on the seafloor, or even on the beach, for that matter. But sea stars, commonly called starfish, have hundreds of tiny feet on the bottom of each of their "arms," also known as rays. These little feet are called tube feet, or podia and help the animals move around, as you can plainly see in the video above. But how do they do it?!

A sea star's podia are filled with sea water, as is the sea star's vascular system. Sea stars are able to transfer water from their vascular systems into their tube feet and then use that pressure to expand them and move around. They even have muscles in their feet that allow them to retract their feet! Want to see it in action? Watch the video!