Cerianthids

Cerianthids are a group of marine animals that belong to the class Anthozoa, which also includes corals and sea anemones. They are characterized by their unique body structure, which consists of a cylindrical or columnar bell-like portion attached to a base, or pedal disc. This peduncle is provided with numerous short, contractile, cilia-like structures that function in movement and sensation. Cerianthids have up to four pairs of short, mutual tentacles around the base of the bell, and four to six longer, usually longer, free tentacles. These tentacles are armed with a series of short, knobbed or conical structures, or defensive spines, that help deter predators.

Cerianthids are carnivores, preying on small invertebrates, which they capture with their tentacles. Most species are benthic, meaning they live on or near the ocean floor. Some species also live in deeper burrows. However, certain species, like Entacmaea quadricolor, can be found in more exposed areas of the intertidal zone.

Most species in this group have a relatively slow growth rate and short lifespan compared to other Anthozoa members. They have a common life strategy of budding, where new animals grow out from the stolon. As a result, colonies of cerianthids consist of many fleshy polyps that are interconnected. There are about 80 species of cerianthids that have been identified worldwide, although details on some members are limited.

Generally, cerianthids provide important ecological services by helping regulate the properties of the substrate and capturing tiny invertebrates that might otherwise cause excessive decomposition.