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 live 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.
Sea Life Melbourne Aquarium is a Southern Ocean and Antarctic aquarium in central Melbourne, Australia. It is located on the banks of the Yarra River beside and under the Flinders Street Viaduct and the King Street Bridge. The attraction is a Sea Life Centre owned by Merlin Entertainments.
The purple-crowned fairy is a species of hummingbird in the subfamily Polytminae, the mangoes. It is found from southeastern Mexico south into northern Peru.
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.
The California mussel is a large edible mussel, a marine bivalve mollusk in the family Mytilidae.
Raja Ampat, or the Four Kings, is an archipelago located off the northwest tip of Bird's Head Peninsula on the island of New Guinea, in Indonesia's Southwest Papua province. It comprises over 1,500 small islands, cays, and shoals surrounding the four main islands of Misool, Salawati, Batanta, and Waigeo, and the smaller island of Kofiau.
Coscinasterias calamaria, or the eleven-armed sea star, is a starfish in the family Asteriidae. It was thought to be endemic to southern Australia and New Zealand but has since been documented as occurring in the Cape Peninsula as well. It is found around low tide levels and deeper, under rocks and wandering over seaweed in pools.
Linckia is a genus of sea stars found mainly in the Indo-Pacific region. They are known to be creatures with remarkable regenerative abilities, and capable of defensive autotomy against predators. They reproduce asexually.
Pisaster ochraceus, generally known as the purple sea star, ochre sea star, or ochre starfish, is a common seastar found among the waters of the Pacific Ocean. Identified as a keystone species, P. ochraceus is considered an important indicator for the health of the intertidal zone.
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.
The purple sunstar, northern sunstar, or smooth sun star, Solaster endeca, is a species of starfish in the family Solasteridae.
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.
Sea star wasting disease or starfish wasting syndrome is a disease of starfish and several other echinoderms that appears sporadically, causing mass mortality of those affected. There are approximately 40 species of sea stars that have been affected by this disease. At least 20 of these species were on the Northwestern coast of Mexico to Alaska. The disease seems to be associated with increased water temperatures in some locales, but not others. It starts with the emergence of lesions, followed by body fragmentation and death. In 2014 it was suggested that the disease is associated with a single-stranded DNA virus now known as the sea star-associated densovirus (SSaDV). However, this hypothesis was refuted by recent research in 2018 and 2020. Sea star wasting disease is still not fully understood.
Marthasterias is a genus of starfish in the family Asteriidae. Both species in the genus are commonly known as the spiny starfish.
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.
Henricia oculata, commonly known as the bloody Henry starfish, is a species of starfish in the family Echinasteridae. It is native to northwestern Europe. It was first described as Asterias oculata by the British zoologist Thomas Pennant in 1777, later being transferred to the genus Henricia.
Asterias rollestoni is a common starfish native to the seas of China and Japan, and not known from the far north or the American coasts of the eastern Pacific.
Labidiaster radiosus, the fragile sticky ray star, is a large species of starfish in the family Heliasteridae and was first described by Lütken in 1871. It is found in the waters of southern South America to Sub-Antarctica and the Antarctic Peninsula.
