''Luidia superba'' is a tropical

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

starfish 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 ...

in the family

Luidiidae ''Luidia'' is a genus of starfish in the family Luidiidae in which it is the only genus. Species of the family have a cosmopolitan distribution. Characteristics Members of the genus are characterised by having long arms with pointed tips frin ...

. A single specimen was found off the Pacific coast of

Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...

in 1888; the species has since been found in the Galapagos Islands. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to this area and has not been recorded elsewhere.

Description

A typical ''Luidia superba'' has five long, tapering arms with pointed tips. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

, the first specimen to be observed and described, had six arms, which was unfortunate as that led to the belief for many years that the normal number of limbs was six. As in other members of the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

, the upper surface of the disc and the arms is covered with paxillae, pillar-like spines with truncated ends. On the underside there are multiple rows of tube feet running down each arm. The colour is greenish-brown above and creamy yellow beneath, the tube feet being tipped with orange. ''Luidia superba'' is probably the largest five-armed starfish in the world. The largest specimen from Tagus Cove in the Galapagos Islands had a radius, measured from the centre of the disc to the tip of the arms, of . Its other dimensions were a disc radius of , a maximum arm width of and a longest spine of . By comparison, a specimen of the ten-armed ''

Luidia magnifica ''Luidia magnifica'', the magnificent star, is a species of starfish in the family Luidiidae. It is found in the Pacific Ocean. Description The magnificent star usually has 10 long, tapering arms with pointed tips though there are occasionall ...

'' from

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

had a radius of and the nine-armed ''

Luidia savignyi ''Luidia savignyi'' is a species of starfish belonging to the family Luidiidae. The species is found in the tropical and subtropical Indo-Pacific region. It is a large starfish and preys on other echinoderms. Description ''Luidia savignyi'' is a ...

'' at was the largest known starfish at the time at which it was measured. The site at Tagus Cove is species rich because of the upwelling of the nutrient-laden, cool water Equatorial Undercurrent nearby, providing an optimum environment for growth which may encourage

gigantism Gigantism ( el, γίγας, ''gígas'', "giant", plural γίγαντες, ''gígantes''), also known as giantism, is a condition characterized by excessive growth and height significantly above average. In humans, this condition is caused by ove ...

Distribution and habitat

The holotype was collected off the coast of Colombia by researchers in the vessel ''R. V. Albatross'' in 1888 at a depth of . This specimen was described by A. H. Clark in 1917 and for a long time was the only known example of the species. Other specimens were later recorded during the Cortez 1, 2 and 3 cruises undertaken to research

Asterozoa The Asterozoa are a subphylum in the phylum Echinodermata. Characteristics include a star-shaped body and radially divergent axes of symmetry. The subphylum includes the class Asteroidea (the starfish), the class Ophiuroidea (the brittle stars ...

in these waters in 1982 and 1985. In 1977, following reports of a similar starfish in the Galapagos Islands, several specimens were observed at night on the seabed of Tagus Cove, Isabela Island, at depths of to . During the day, the starfish bury themselves under about of sand, the only clue to their presence being a depression in the sand surface. In that location, these starfish were quite common in 1977, there being about one individual per 10 square metres (yards) of seabed. More recently, the

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event of 1982–3 was particularly severe and afterwards, ''Luidia superba'' was no longer to be found in its previous location in Tagus Cove. Its fate in the Galapagos Islands remains unclear.

Biology

The stomachs of the three specimens taken from Tagus Cove were examined to determine their diet. Unfortunately they were empty except for a few sea urchin spines, but like other members of its

, ''Luidia superba'' is likely to be an opportunistic

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...

of large

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoo ...

and a

scavenger Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While scavenging generally refers to carnivores feeding on carrion, it is also a herbivorous feeding b ...

. Related species feed mainly on

bivalve molluscs Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

, brittle stars and

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

References

{{Taxonbar, from=Q2443705 Luidia Fauna of the Pacific Ocean Animals described in 1917 Taxa named by Austin Hobart Clark