Feather Stars & Sea Lilies
Referred to as crinoids, starfish of the class Crinoidea, which means "lily-like", can generally be divided into two categories; "stalked" crinoids referred to as Sea Lilies, and "unstalked" crinoids referred to as Feather Stars, or comatulids.
These starfish inhabit seas around the world, but are mainly restricted to depths greater than 200m (about 650 feet), with the shallowest occurring at 100m (about 300 feet). The large majority of living comatulids (Feather Stars) can be found on deep water shelves in tropical Indo-West Pacific waters, which is the richest region.
Feather Star species such as Florometra serratissima and Himerometra palmata, like all crinoids, are passive suspension feeders that live on a variety of microscopic organisms (i.e. diatoms and other unicellular algae, foraminiferans and actinopods), invertebrate larvae, small crustaceans, and detrital particles. They rely on ambient water movement to bring food to them where they use their featherlike arms to collect suspended particles drifting by, envelope it in a mucus coating and then transport the captured food to their mouth by means of cilitray tracts.
These unusual and delicate starfish attach themselves by means of root-like appendages called cirri found at their base, which they utilize to crawl around with as well. Most remain immobile once they find a good feeding spot, but some hide in caves or under ledges during daylight hours, then move out to the top of the reef at night to feed. They can also swim by flapping their feathery arms, which is something most often done when disturbed.
With opposite sexes, these starfish spawn in the water. Some species hatch out as free-swimming larvae that settle on the bottom and transform into juveniles and then mature into adults, some others hatch as miniature adults, while some females even hold the eggs in their arms until they hatch.
Feather Stars and Sea Lilies are seldom kept in aquariums because of their sensitive nature and specialized feeding and captive care requirements. To learn more about the natural history, ecology, biology, and other characteristic of starfish members of the class Crinoidea, we recommend the following reference resources: