Order Apodida
Wormlike holothurians with rough or warty surface, without tubefeet (except on tetacles). Body wall very thin. Without anal papillae, respiratory trees, and tetacle ampullae. Simple, digitate or pinnate tentacles (10-25). Ossicles absent in a few species, but usually including anchors, anchor plates, or wheels. Species usually small, upto a few centimetres; some tropical species, however, can reach a length of 2 m. Larval stages usually pelagic, but some species are viviparous. Apodids usually live under rocks or burrowing in the sand in shallow water.