Apodida

Brandt, 1835

3 Families; 34 Genera, 8 monotypic; 269 species

More of less cylindrically elongated holothurians with a terminal mouth, respiratory trees and anal papillae absent; with a greatly reduced water vascular system; circumoral tentacles, either simple, pinnate, or digitate, are present but lack ampullae; there are no pedicels or papillae; circular muscles of body wall continuous, i.e., not broken or interrupted at radii; characteristic sense organs, present, situated beside radial nerves, near nerve ring; minute ciliated funnels, apparently having an excretory function, usually positioned in body cavity or near mesenteries; calcareous deposits, in form of anchors and plates, wheels or sigmoid bodies usually present, but no tables or phosphatic deposits. (Clark, 1907)

Tentacles simple, digitate or pinnate, retractor muscles, tubefeet, and respiratory trees absent. Body vermiform. Calcareous deposits include anchors, anchor plates, wheels, and sigmoid rods; sometimes absent. (Pawson, 1965)