Forcipulatida

Forcipulatida is an order of echinoderms belonging to the class Asteroidea, commonly known as starfishes or sea stars. This order is characterized by the presence of prominent pedicellariae, which are small, pincer-like organs used for defense, cleaning, and capturing small prey. These pedicellariae are typically stalked and have a distinctive forcep-like appearance, hence the name "forcipulatida."

Members of Forcipulatida are found in marine environments worldwide, inhabiting a wide range of depths from shallow coastal waters to the abyssal plains. They exhibit diverse feeding strategies, with many species being predators that feed on mollusks, crustaceans, and other invertebrates. Their body plan is typically pentamerous, meaning they have five arms radiating from a central disc, although some species may have more.

A key feature distinguishing Forcipulatida from other sea star orders is the structure of their ambulacral ossicles, which are small bones that support the tube feet used for locomotion. In Forcipulatida, these ossicles are often paired and articulate in a way that provides flexibility and strength to the arms. This order includes many well-known and common sea star species, making them a significant component of marine ecosystems. Examples of genera within Forcipulatida include Asterias, Pisaster, and Coscinasterias.