The Apodida is an order of littoral to deep-sea, largely infaunal holothurians. This order comprises three families, 32 genera and about 270 known species, called apodids.
Characteristics
Members of this order have a circum-oral ring and tentacles, but do not have tube feet or radial canals. They are worm-like in form, adapted for burrowing through the sediment in a fashion similar to earthworms. The absence of tube feet gives the order its name, Apodida meaning without feet. They also lack the complex respiratory trees found in other sea cucumbers, and respire and excrete nitrogenous waste through their skin.