About Anneissia bennetti (Müller, 1841)
Anneissia bennetti is one of the larger species in the Comatulidae family, growing up to 30 cm. It is a filter feeder, which means it does not actively hunt food; instead, it captures food particles suspended in the water column for consumption. It does this using 31 to 120 feathery arms, which it typically holds upward into the water to catch food. It feeds on detritus, phytoplankton, and zooplankton. Its arms are covered in numerous small, finger-like appendages called pinnules, which increase the surface area available to trap food particles. The mouth of Anneissia bennetti sits on the upper surface of its large, thick central body, which is called the centrodorsal. Many long, robust cirri measuring 3 to 4.5 cm long attach to the centrodorsal. Early in their life, after larvae settle out of the water column, these cirri are used to grip the substrate. Young individuals start life attached to a stalk, which holds them to the substrate via the cirri. Once they reach maturity, they can break the stalk and become free-living. Even after becoming free-living, they still use their cirri to elevate their bodies, positioning them to better trap food. The combination of long, robust cirri and the posture this gives Anneissia bennetti makes it easy to distinguish this species from other similar species. Unlike many other crinoid species, Anneissia bennetti is diurnally active, meaning it is active during the day. The body color of this species is quite variable, ranging from yellow to brown to purple. The tips of the pinnules are often more brightly colored than the arms and centrodorsal. Anneissia bennetti is widespread across the Indo-West Pacific, ranging from the Bay of Bengal and Maldives to the Marshall Islands, and from China south to Australia, Bali, and Indonesia. It is most commonly found at depths between 5 and 25 meters, though a less common deep water variety lives at depths between 15 and 45 meters. This species prefers to live on exposed coral heads, and is rheophilic, meaning it favors habitats with stronger water currents. This positioning ensures more food particles flow past the animal, increasing its nutrient uptake.
