Feather Star ( Florometra serratissima )
by Scott Boyd
The Feather Star, is a delicate, 10 armed Crinoid with slender, feather-like arms that wave in moderate currents looking for plankton to eat. They utilize root-like cirri at their base to grasp firmly to hard substrates. While feeding, the arms are alternately curled slowly inward to bring plankton to the mouth. This is mesmerizing to watch, and is similar to the movement used by the feather star to swim through the water. Relatively common in Puget Sound waters, the arms of the feather star grow to about 10”. They are range from Alaska to Baja California at depths ranging from shallow to 3300 ft.
Surveys taken off Vancouver Island suggest that as many as 80% of feather stars had one or more regenerating arms due to predation by Decorator Crabs and Sunflower Stars. Fortunately, they are able to regenerate arms rather quickly given adequate supplies of plankton ( mostly larva ). Scattered individuals are very common among the hydroids and bryozoa that cover rocks, especially on vertical and undercut faces. The photo shows my favorite location for observing large clusters of Feather Stars, on the bridge of the HMCS Saskatchewan near Nanaimo, B.C.
Crinoids are echinoderms, relatives of the sea urchin, starfish and brittle star, which all have five-fold symmetry and a skeleton of calcite plates. Feather stars are often confused with brittle stars, which also lift their arms into the water to feed. However, brittle stars have only five arms, not ten.
Feather Stars reproduce in the spring and early summer. Free floating eggs hatch into larvae which swim for one or two days until they find a site to attach to. There, each grows into a tiny stalked crinoid, a miniature version of the fossil and deep-sea species. Finally they develop cirri at the base and break free of the stem, which is left to die while the little Feather Star begins its adult life.