Sea stars dance to their own rhythm: This one is called “The Ambulacral Groove.”
Sea stars amble about with hundreds of tiny tube feet—lovely hydraulically powered limbs unique to echinoderms, which include sea urchins and sea cucumbers. Often equipped with sticky mucus and small suction cups, tube feet make sea stars highly ambulatory.
Sea stars have five V-shaped channels for their tube feet to take a hike. These ambulacral grooves are named after the latin “ambulacrum”, meaning a walk planted with trees. The term has even deeper roots in the Indo-European “ambhi”, meaning “around.”
Of course, having your bare feet exposed to the seafloor can be a bit touchy—fortunately, the ambulacral grooves are protected by spines and ossicles that can close off the tube feet from the rest of the world if things get socked in.
Tube feet are groovy, to say the least. And if you thought a two-step was tough, try a hundred step!