Genera: ± 600 species.
Habitat: marine.
ZoologyCrinoidea are marine animals. Their mouth is located on the upper surface, surrounded by feeding arms, and is linked to a U-shaped gut. Their anus is located on the oral disc near the mouth.
They have the basic echinoderm pattern of fivefold symmetry, mostly the arms subdivided into ten or more arm. The arms have feathery pinnules and are spread wide to gather planktonic particles from the water. At some stage in their lives, most crinoids have a stem used to attach themselves to the substrate, but many live attached only as juveniles and become free-swimming as adults.
CladesArticulataBourgueticrinida: sea lilies; attached to the sea bottom by a stalk.
Comatulida: feather stars; unstalked.
Cyrtocrinida: sea lilies; attached to the sea bottom by a stalk.