Feather stars are sea animals that belong to the phylum Echinodermata and the class Crinoidea. A feather star is not the same as a starfish (also known as a sea star and sometimes misspelled as star fish). Close relatives of feather stars include sea stars, brittle stars, sea cucumbers and sea urchins. Feather stars inherit their name from the feathery appearance of their arms. A feather star habitat is slightly different from a starfish habitat.
Feather Star Habitat
Feather stars, also called crinoids, reside in the ocean, typically in shallow, warm waters. Some species do, however, exist in colder waters and deeper areas. A feather star habitat differs from a starfish habitat in a number of ways. A sea star or starfish habitat needs the right surface for the creature’s feet to move across. Sea stars with tube feet reside among rocks, and sea stars with pointed tube feet tend to live on the seabed in sand or mud. Feather stars, however, live in areas with strong currents. They do not tend to live around silt, which can clog their feet. Living in areas with these currents ensures their survival, as they yield more opportunities to capture food. They may also swim through the water column if disturbed.
Feather Star Anatomy
Crinoids represent one of the oldest forms of echinoderms and can be found in fossils dating back hundreds of millions of years. Like sea stars and other echinoderms, feather stars possess a form of internal skeleton. Calcium carbonate plates comprise this skeleton, which is covered by a skin. Ligaments and muscles hold the body together. Feather stars, like other echinoderms, exhibit radial symmetry, in which their mouths lie at the center of their several branching arms.
Feather stars, like their relatives, also have four body parts. These include the holdfast, to anchor to the seafloor; the stem, a muscle-filled part to raise the calyx; the calyx, which is cup-shaped and comprised of internal organs; and of course its arms. The arms vary in numbers based on fives. These branchlike, feathery arms are called pinnules. The arms curl in while the feather star rests and spread out when they feed or when they swim. Cirri represent tiny legs used for attachment of feather stars to substrates. Like starfish and other echinoderms, injured feather stars can regenerate their arms.
Feather stars rely upon their anatomy for camouflage, as they resemble their surrounding neighbors such as corals, sea anemones and plants. In shallow water, however, feather stars may exhibit vivid colors.