Pedicellaria

Enlarged Pedicellariae of Echinus

A pedicellaria (plural. pedicellariae) is a small wrench or claw-shaped structure commonly found on Echinoderms, particularly in sea stars (class Asteroidea) and sea urchins (class Echinoidea). Pedicellariae are poorly understood but in some taxa, they are thought to keep the body surface clear of algae, encrusting organisms, and other debris in conjunction with the ciliated epidermis present in all echinoderms. Pedicellariae in some taxa, such as the deep-sea Brisingida, and the Antarctic Labidiaster are known to function in food capture. In forcipulate sea stars, each pedicellaria is typically composed of three forceps-like valves. Other asteroids can have pedicellariae composed of only two components. In some asteroid sea stars pedicellariae are present around the base of a spine or on the surface of the animal's body. In other sea stars, they are present in pits on the abactinal, marginal, or actinal surface; oftentimes on the adambulacral plate adjacent to the tube foot furrow.