Crinoids (Overview)

Details

Crinoids (class Crinoidea) comprise stalked sea lilies and unstalked feather stars. They are suspension feeders that capture plankton and particulate organic matter with sticky tube feet on pinnules and convey food along ambulacral grooves to the mouth.

Ecology & Biology

• Feeding: most efficient in moderate currents; filter micro‑zooplankton and POM.

• Life modes: deep sea—mainly stalked forms; shallow reefs—feather stars gripping with cirri, crawling and repositioning.

• Activity: many are nocturnal, spreading their feathery arms at night.

• Regeneration: frequent arm autotomy and regrowth; some species propagate via fragments.

Identification

A central calyx bears usually ~10 arms (often more by branching); arms carry pinnules forming the feathery outline. Stalked forms have a segmented, calcareous stalk and holdfast; feather stars use cirri. All show echinoderm pentamerous symmetry.

Size & Longevity

• Arm span: typically 10–30 cm; large feather stars 50–70+ cm; sea‑lily stalks 1–2+ m.

• Life: generally multi‑year; deep‑sea taxa may be very long‑lived.

Range & Habitat

Global in distribution—from shallow coral reefs to abyssal plains and seamounts. Feather stars are common on current‑swept walls and among gorgonians/black corals; sea lilies dominate many cold deep‑water settings.

Roles & Threats

• Roles: mediate particulate flux; provide microhabitats for commensal crustaceans and fishes.

• Threats: bottom trawling and deep‑sea mining, sedimentation, pollution, warming and acidification.

IUCN: overview entry; conservation is species‑specific. Marked here as Not Evaluated (NE).