| Ophidiaster granifer | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Valvatida |
| Family: | Ophidiasteridae |
| Genus: | Ophidiaster |
| Species: | O. granifer |
| Binomial name | |
| Ophidiaster granifer | |
| Synonyms [1] | |
| |
Ophidiaster granifer, the grained seastar, is a species of starfish in the family Ophidiasteridae. It is found in the Red Sea and the Indo-Pacific and is the only known species of starfish to reproduce by parthenogenesis.
Ophidiaster granifer is a small five armed starfish with a cryptic mottled brown colouration. It has a rough, granular appearance and grows to a diameter of about 10 cm (4 in). The disc is quite small and the medium-length, fairly broad arms have rounded tips. [2] [3] [4]
No male Ophidiaster granifer has ever been identified and all known adults are female. [4] As far as is known, Ophidiaster granifer is the only member of the phylum Echinodermata to reproduce exclusively by parthenogenesis. In this species, eggs are liberated into the sea in a synchronous spawning event but no fertilisation takes place. The eggs are large, with a diameter of 0.6 millimetres (0.024 in) and the mother attaches some of them to the underside of boulders. Here they develop until they undergo metamorphosis into juvenile starfish. Other eggs are planktonic and drift with the currents. In either case, the larvae are lecithotrophic and feed off the yolks of their eggs. This reproductive strategy may be linked to the starfish's low fecundity rate and its low population density. [4]
Ophidiaster granifer is found on coral reefs in shallow waters in the Red Sea and Indo-Pacific Ocean. It is known from the South China Sea, Japan, Tonga, Fiji, Samoa, northern and western Australia, the Great Barrier Reef, New Guinea, Indonesia, the East Indies and the Philippines. It usually hides under boulders and is found on outer reef flats and patch reefs in lagoons, among broken coral rubble and among the dead bases of tangled coral thickets. [1] [4]
An echinoderm is any member of the phylum Echinodermata. The adults are recognisable by their radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the sea lilies or "stone lilies". Adult echinoderms are found on the sea bed at every ocean depth, from the intertidal zone to the abyssal zone. The phylum contains about 7,000 living species, making it the second-largest grouping of deuterostomes, after the chordates. Echinoderms are the largest entirely marine phylum. The first definitive echinoderms appeared near the start of the Cambrian.
Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or basket stars. Starfish are also known as asteroids due to being in the class Asteroidea. About 1,900 species of starfish occur on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at 6,000 m (20,000 ft) below the surface.
The crown-of-thorns starfish, Acanthaster planci, is a large starfish that preys upon hard, or stony, coral polyps (Scleractinia). The crown-of-thorns starfish receives its name from venomous thorn-like spines that cover its upper surface, resembling the biblical crown of thorns. It is one of the largest starfish in the world.
The Ophidiasteridae are a family of sea stars with about 30 genera. Occurring both in the Indo-Pacific and Atlantic Oceans, ophidiasterids are greatest in diversity in the Indo-Pacific. Many of the genera in this family exhibit brilliant colors and patterns, which sometimes can be attributed to aposematism and crypsis to protect themselves from predators. Some ophidiasterids possess remarkable powers of regeneration, enabling them to either reproduce asexually or to survive serious damage made by predators or forces of nature. Some species belonging to Linckia, Ophidiaster and Phataria shed single arms that regenerate the disc and the remaining rays to form a complete individual. Some of these also reproduce asexually by parthenogenesis.
Asterias amurensis, also known as the Northern Pacific seastar and Japanese common starfish, is a seastar found in shallow seas and estuaries, native to the coasts of northern China, Korea, far eastern Russia, Japan, Alaska, the Aleutian Islands and British Columbia in Canada. Two forms are recognised: the nominate and formarobusta from the Strait of Tartary. It mostly preys on large bivalve molluscs, and it is mostly preyed on by other species of starfish. Population booms in Japan can affect the harvest of mariculture operations and are costly to combat.
Culcita is a genus of cushion stars. They are found in tropical waters. Some are kept in home aquariums.
Acanthaster is a bitypic genus of large and venomous starfish placed in its own family, Acanthasteridae. Its two members are known as crown-of-thorns starfish. Acanthaster are native to Coral reefs in Indo-Pacific region. They are a contributor to coral reefs degradation because at high density they consume a large amount of live coral.
Choriaster is monotypic genus in the family Oreasteridae containing the single species Choriaster granulatus commonly known as the granulated sea star. Other common names include big-plated sea star and doughboy starfish. This species is harmless to humans.
Hymenocera picta, commonly known as the harlequin shrimp, is a species of saltwater shrimp found at coral reefs in the tropical Indian and Pacific Oceans. It is usually considered the only species in the genus Hymenocera, but some split it into two species: H. picta from the central and east Pacific, where the spots are deep pinkish-purple with a yellow edge, and H. elegans from the Indian Ocean and west Pacific, where the spots are more brownish and have a blue edge. They reach about 5 cm (2.0 in) in length, live in pairs, and feed exclusively on starfish, including crown-of-thorns starfish. They do seem to prefer smaller, more sedentary starfish, but as these generally are not sufficiently numerous for their needs, they commonly attack crown-of-thorns starfish, both reducing its consumption of coral while under attack, and killing it within a few days.
Leptasterias hexactis is a species of starfish in the family Asteriidae, commonly known as the six-rayed star. It is found in the intertidal zone of the western seaboard of the United States. It is a predator and is unusual among starfish in that it broods its eggs and young.
Solaster dawsoni, the morning sun star, is a species of starfish in the family Solasteridae. It is found on either side of the northern Pacific Ocean. It has two subspecies:
Pteraster tesselatus, the slime star or cushion star, is a species of starfish in the family Pterasteridae found in the North Pacific.
Acropora cytherea is a stony coral which forms horizontal table like structures. It occurs in the Indo-Pacific Ocean in areas with little wave action, favouring back reef environments from 3 to 20 m depth.
Acropora pulchra is a species of colonial staghorn coral in the family Acroporidae. It is found on the back fringes of reefs in shallow water in the western Indo-Pacific Ocean. The oldest fossils of this species date back to the Pleistocene.
Iconaster longimanus, the icon star or double star, is a species of starfish in the family Goniasteridae. It is found in the west and central Indo-Pacific Ocean. The genus name comes from the Greek eikon, meaning portrait or image and possibly referring to the way the marginal plates frame the disc, and aster, meaning star. The specific name comes from the Latin longus manus and refers to the long, slender arms.
Cynarina lacrymalis is a species of stony coral in the family Lobophylliidae. It is variously known as the flat cup coral, solitary cup coral, button coral, doughnut coral, or cat's eye coral. It is found in the western Indo-Pacific Ocean and is sometimes kept in reef aquaria.
Fromia milleporella, common name red starfish or black spotted starfish, is a species of starfish belonging to the family Goniasteridae.
Neoferdina cumingi, also known as Cuming's sea star, is a species of starfish in the family Goniasteridae. It is native to the tropical Indo-Pacific region.
Echinaster callosus, the warty sea star or the banded bubble star, is a species of starfish found in shallow parts of the western Indo-Pacific region. The disc and five slender arms are covered with white, pink, red or violet warts, often forming transverse bands of colour on the arms.
Coscinasterias muricata is a species of starfish in the family Asteriidae. It is a large 11-armed starfish and occurs in shallow waters in the temperate western Indo-Pacific region.