| Oxycomanthus bennetti | |
|---|---|
 | |
| Oxycomanthus bennetti | |
| Scientific classification | |
| Kingdom: | |
| Phylum: | |
| Class: | |
| Subclass: | |
| Order: | |
| Family: | |
| Genus: | |
| Species: | O. bennetti |
| Binomial name | |
| Oxycomanthus bennetti (Müller, 1841) | |
| Synonyms | |
| |
Oxycomanthus bennetti, the Bennett's feather star, is a species of crinoid belonging to the family Comatulidae. [1] It is found in shallow water in the Indo-Pacific between northern Australia and southeast Asia. [2]
Oxycomanthus bennetti is one of the larger species of Comatulidae, growing up to 30 cm. [3] It is a filter-feeder, meaning it does not hunt down food, it captures food suspended in the water column to eat. It does this with 31–120 feathery arms, usually held up into the water in order to trap food, feeding on detritus, phytoplankton and zooplankton. The arms have numerous finger-like appendages known as pinnules, in order to increase the surface area on which food can be trapped. The mouth is on the upper side of the large, thick body, otherwise known as the centrodorsal. Attached to the centrodorsal are many long, robust cirri (3-4.5 cm). These cirri are used by O. bennetti to hold on to substrate in the beginning portion of their lives, after the larvae settle out of the water column. They begin their lives attached to a stalk, held onto a substrate by cirri, and once mature, they can break the stalk and become free-living. Once they are free-living, however, they still use these cirri to elevate themselves to put themselves in a better position to trap food. Because these cirri are so long and robust, the posture of O. bennetti can be used to easily distinguish it from other similar species. O. bennetti is diurnally active, meaning it is active during the day, unlike many other species of crinoids. The color of this species is quite variable, ranging from yellow to brown and purple. The tips of the pinnules are often more brightly colored than the arms and centrodorsal. [4]
O. bennetti is widespread in the Indo-West Pacific, from Bay of Bengal and Maldives to the Marshall Islands and from China to Australia, Bali and Indonesia. It is most commonly found between 5 and 25 meters depth, but there is a less common deep water variety that lives between 15 and 45 meters depth. O. bennetti prefers to inhabit exposed coral heads, and is rheophilic, meaning it prefers to live where currents flow more strongly. [5] [6] This positioning ensures that more food floats past the star, therefore increasing nutrient uptake.
O. bennetti is gonochoric, meaning it has both female and male individuals. Reproduction occurs when some of the pinnules burst, releasing gametes into the water column. Sperm will fertilize eggs, which will hatch to produce free-swimming larvae. These larvae settle after a few days, where they begin to produce their stalk and start to grow. [7] O. bennetti has been observed having a symbiotic relationship with various species of polychaete worms. This relationship has been described as commensalistic, meaning that the polychaete worms benefit greatly from the feather star, as it provides shelter, protection, and food, and there is little to no negative effect on O. bennetti. Individuals of the species Hololepidella laingensis and Paradyte crinoidicola have been found on O. bennetti in Papua New Guinea, with an average of 2–4 worms per individual star, as competition between these worms is fierce. [8] In Vietnam, these stars were found with a total of 11 symbiont species on only 18 individuals, [9] meaning that these feather stars serve as excellent shelters for smaller animals looking for protection and food.
 |  |  |
Crinoids are marine animals that make up the class Crinoidea, one of the classes of the phylum Echinodermata, which also includes the starfish, brittle stars, sea urchins and sea cucumbers. Those crinoids which, in their adult form, are attached to the sea bottom by a stalk are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, being members of the largest crinoid order, Comatulida.
Comasteridae is a family of crinoids.
Antedon bifida is a species of crinoid in the family Antedonidae commonly known as the rosy feather star. It is found in north west Europe.
Antedon petasus is a marine invertebrate, a species of crinoid or feather star in the family Antedonidae. It is found around the coasts of north west Europe.
Comatulida is an order of crinoids. Members of this order are known as feather stars and mostly do not have a stalk as adults. The oral surface with the mouth is facing upwards and is surrounded by five, often divided rays with feathery pinnules. Comatulids live on the seabed and on reefs in tropical and temperate waters.
Davidaster discoideus or the beaded crinoid is a species of feather star in the family Comatulidae. It was previously known as Nemaster discoidea but the World Register of Marine Species has determined that the valid name is Davidaster discoideus. It is found on reefs in the Caribbean Sea and northern coast of South America.
Comaster schlegelii, the variable bushy feather star, is a crinoid in the family Comatulidae. It was previously classified as Comanthina schlegeli but further research showed that it was better placed in the genus Comaster. It is found on shallow water reefs in the western Pacific Ocean.
Metacrinus rotundus, the Japanese sea lily, is a marine invertebrate, a species of stalked crinoid in the family Isselicrinidae. It is a species found off the west coast of Japan, and is living near the edge of the continental shelf, around 100–150m deep. This is the shallowest species among the extant stalked crinoids.
Himerometra robustipinna is a species of crinoid belonging to the family Himerometridae.
Antedon mediterranea is a species of stalkless crinoid in the family Antedonidae, commonly known as the Mediterranean feather star. It is found on the seabed at moderate depths in the Mediterranean Sea. It is a filter feeder and captures plankton with its long feathery arms.
Bourgueticrinida is an order of crinoids that typically live deep in the ocean. Members of this order are attached to the seabed by a slender stalk and are known as sea lilies. While other groups of crinoids flourished during the Permian, bourgueticrinids along with other extant orders did not appear until the Triassic, following a mass extinction event in which nearly all crinoids died out.
Leptometra celtica is a marine invertebrate and species of crinoid or feather star of the Leptometra genus in the family Antedonidae. It is found in the Atlantic Ocean around the coasts of north west Europe. The presence of L. celtica and L. phalangium is considered to be a good indication of nearby shelf breaks, general bottom currents, and areas of high gross productivity as they are suspension-feeders, hence their proliferation in productive environments.
Comatulidae is a family of comatulid crinoids. Since 2015, it replaces the family Comasteridae.
Florometra serratissima is a species of crinoid or feather star in the family Antedonidae. It is found off the Pacific coast of North America, usually in deep water.
Endoxocrinus parrae is a species of stalked crinoids of the family Isselicrinidae. It is the most commonly found isocrinine species in west Atlantic Ocean.
Promachocrinus is a genus of free-swimming, stemless crinoids. It is a monotypic genus, and the only species in the genus is Promachocrinus kerguelensis. This is a coldwater crinoid which is found in the seas around Antarctica and surrounding island groups, including under the sea ice.
Aporometra wilsoni is a marine invertebrate, a species of crinoid or feather star in the family Aporometridae. It is found in shallow water around the coasts of southern Australia.
Notocrinus virilis is a marine invertebrate, a species of crinoid or feather star in the family Notocrinidae. It is found in deep water in the Southern Ocean around the coasts of Antarctica and adjacent islands. A sea snail sometimes parasitizes it.
Aporometra paedophora is a marine invertebrate, a species of crinoid or feather star in the family Aporometridae. It was first found at a depth of 22 fathoms off the Manning River on the New South Wales coast. Other specimens were found off the coast of Bunbury, Western Australia at depths between 9 and 15 m. Based on morphological evidence of four specimens of A. paedophora, Helgen & Rouse believe that this may not be a separate species from Aporometra wilsoni.
Cenometra bella is a species of crinoids belonging to the genus Cenometra. They can have up to 30 arms and can be of variable colours but are often characterised by a marked contrast between the extending free-arms and the feathery pinnules. This species clings to its support and moves around by its feet-like cirri.