Feather Stars (Crinoids)

Feather Stars (Crinoids)

Life thrives on the Shallow Profiler Platform including feather stars (crinoids; left), brittle stars, and translucent scallops. Credit: UW/NSF-OOI/WHOI; J2-1514; V23.

Suspension-feeding, unstalked crinoids (also known as feather stars) are a common sight on the Shallow Profiler platforms, particularly near the coast. Crinoids are echinoderms (like sea stars, brittle stars, and sea urchins), and although they are similar to sea stars in appearance, they are not closely related. These ancient animals used to be much more diverse, but the 700 existing species are found in both shallow water as well as abyssal depths. Stalked forms are also known as "sea lilies" (which is the origin of the name: ‘crinoid’ means ‘lily-like’ in Ancient Greek). Some species live attached only as juveniles and become free-swimming as adults.

The mouth of the crinoid is located on the upper surface, surrounded by 10 or more subdivided feeding arms with feathery pinnules that are used to filter plankton and other food particles from the seawater. The pinnules are covered with sticky tube feet that grab the particles and flick them into a groove lined with cilia that transport them to the mouth. The anus is also on the oral disc, next to the mouth, linked to a U-shaped gut.

The crinoids we encounter on OOI platforms are likely Florometra serratissima, which are found in Pacific Ocean offshore waters from Alaska to Baja California.