pedicellaria

Pedicellariae are small, pincer-like appendages on the external surface of many echinoderms, especially sea urchins (Echinoidea) and starfish (Asteroidea). They arise from the epidermis and are connected to the skeleton by muscles and connective tissue. Each pedicellaria consists of a stalk that bears one or more calcareous valves at its tip, which can be opened or closed by muscular action.

Different forms exist, including clasping pedicellariae with movable jaws and venomous types that carry venom glands in some species. They function as a defensive and cleaning apparatus: they can deter or attack small epibionts, remove attached debris, and sometimes capture tiny prey items. Their activity helps maintain the animal’s surface free of fouling organisms and parasites, and provides a first line of defense against potential grazers or encrusting organisms.

Pedicellariae are particularly conspicuous on sea urchins, where some varieties are venomous, but they are also present on many starfish and other echinoderms. In some taxa they play a diagnostic role for identification and contribute to the overall morphology studied in echinoderm systematics.

Research into pedicellariae provides insight into echinoderm anatomy, the evolution of defensive structures, and the functional integration of epidermis with the water vascular system.