''Diplasterias brucei'' is a

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 Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Asteriidae. It is found in the Pacific Ocean and Southern Ocean. It is a

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 ...

and

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 ...

and is unusual among starfish in that it broods its young.

Description

''D. brucei'' usually has five arms, but in the vicinity of

South Georgia South Georgia ( es, Isla San Pedro) is an island in the South Atlantic Ocean that is part of the British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. Stretching in the east� ...

, a six-armed form is common. This starfish varies in colour from a pale bluish-green to a yellowish or orange hue. The maximum size is about across.''Diplasterias brucei''; (Koehler, 1908)
Antarctic Field Guide. Retrieved 10 February 2017.

Distribution

''D. brucei'' is found in the Pacific Ocean and Southern Ocean. In Antarctica, the species is found on the seabed in the

Antarctic Peninsula The Antarctic Peninsula, known as O'Higgins Land in Chile and Tierra de San Martín in Argentina, and originally as Graham Land in the United Kingdom and the Palmer Peninsula in the United States, is the northernmost part of mainland Antarctic ...

and in

East Antarctica East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almost ...

, at depths down to about .

Ecology

''D. brucei'' is one of the more conspicuous animals in the zone deeper than which is the lower limit for anchor ice formation. This zone is characterised by a layer of sponge

spicules Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: *Spicule (sponge), small skeletal elements of sea sponges *Spicule (nematode), reproductive structures found in male nematodes ( ...

and dead mollusc shells a metre or more thick, swathed in living

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through t ...

s. This matrix is a biodiverse environment rich in

sea anemone Sea anemones are a group of predation, predatory marine invertebrates of the order (biology), order Actiniaria. Because of their colourful appearance, they are named after the ''Anemone'', a terrestrial flowering plant. Sea anemones are classifi ...

polychaete worms Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...

, hydroids,

bryozoa Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

ns and molluscs. The bivalve mollusc '' Limatula hodgsoni'' is particularly common and there are also great quantities of tiny gastropod molluscs in the genera '' Onoba'' and ''

Margarella ''Margarella'' is a genus of sea snails, marine gastropod molluscs in the subfamily Margarellinae of the family Calliostomatidae.Bouchet, P. (2012). Margarella Thiele, 1893. Accessed through: World Register of Marine Species at http://www.marine ...

''. The starfishes ''

Acodontaster conspicuus ''Acodontaster conspicuus'' is a species of starfish in the family Odontasteridae. It is found in the Southern Ocean, in the waters off Antarctica and the island groups nearby. Description ''Acodontaster conspicuus'' grows to about 30 cm ( ...

'', '' Acodontaster hodgsoni'', ''

Odontaster meridionalis ''Odontaster'' is a genus of sea stars. The type species is ''Odontaster hispidus''. Species The following species are listed in the World Register of Marine Species: *'' Odontaster aucklandensis'' McKnight, 1973 *'' Odontaster australis'' H.L. ...

'' and '' Perknaster fuscus'' feed on the sponges, while '' Odontaster validus'' mostly scavenges, and ''D. brucei'' and the gastropod '' Trophonella longstaffi'' both feed on the bivalve ''L. hodgsoni''. ''D. brucei'' primarily feeds on molluscs, but does not seem to eat sponges as do many other starfish. It is sometimes preyed on by the sea anemone '' Urticinopsis antarctica''. Developing embryos of this species are brooded by the female until they have developed into juvenile starfish. The starfish ''O. validus'' is an omnivorous predator and scavenger in Antarctic waters, a

keystone species A keystone species is a species which has a disproportionately large effect on its natural environment relative to its abundance, a concept introduced in 1969 by the zoologist Robert T. Paine. Keystone species play a critical role in maintaini ...

feeding on almost anything organic with which it comes in contact, including other species of starfish.''Odontaster validus''; Koehler, 1906
Antarctic Field Guide. Retrieved 10 February 2017. However, ''O validus'' avoids the brooded embryos of ''D. brucei'', which contain secondary metabolites which act as a deterrent. This is of importance in a species that takes a long time to develop in the cold waters which it inhabits.

References

{{Taxonbar, from=Q2221801 Asteriidae Animals described in 1908