''Asterodiscides truncatus'', the firebrick starfish, is a species of five-armed

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

in the family

Asterodiscididae Asterodiscididae is a family of starfish. Members of the family have five short tapering arms and a wide disc. The family was first described by the Australian zoologist F.W.E. Rowe in 1977. Genera The following genera are listed in the World Re ...

. It is native to eastern and southern Australia, the

Norfolk Ridge The Norfolk Ridge (Norfolk Island Ridge, Norfolk Rise, South New Caledonia Ridge) is a long submarine ridge running between New Caledonia and New Zealand, about off the east-coast of Australia. It is part of a complex region of ridges between ...

and the

Kermadec Islands The Kermadec Islands ( ; ) are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand. They are in total area and uninhabit ...

of New Zealand.

Description

The starfish has

plates Plate may refer to: Cooking * Plate (dishware), broad, mainly flat vessel commonly used to serve food * Plates, tableware, dishes or dishware used for setting a table, serving food and dining * Plate, the content of such a plate (for example: ...

on its aboral (upper) surface arranged in a reticulate fashion with brightly coloured

tubercles In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projection, b ...

scattered between them. There are only a few inconspicuous marginal plates but the superomarginal plate at the end of each arm is very large. The

tube feet Tube or tubes may refer to: * Tube (2003 film), ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM#Tubes, Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/e ...

are tipped with suckers and do not have any spicules. The tubercles vary in size and colour, making a red, purple and orange pattern on the aboral surface. There is a pair of very large tubercles at the tip of each arm.

Distribution and habitat

Endemic Endemism is the state of a species being found only 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 foun ...

to Australia, ''A. truncatus'' occurs on the south and east coasts, on the western end of the

and the

. In southern Australia it is a deep water species found in rocky habitats at , but in New South Wales it occurs on shallow rocky reefs in the

subtidal zone The neritic zone (or sublittoral zone) is the relatively shallow part of the ocean above the drop-off of the continental shelf, approximately in depth. From the point of view of marine biology it forms a relatively stable and well-illuminated ...

Ecology

''Asterodiscides truncatus'' feeds by grazing on sponges and other colourful benthic organisms at the base of the

kelp forest Kelp forests are underwater areas with a high density of kelp, which covers a large part of the world's coastlines. Smaller areas of anchored kelp are called kelp beds. They are recognized as one of the most productive and dynamic ecosystems on E ...

, amongst which its bright colours are inconspicuous. A

commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit f ...

shrimp can sometimes be found living among the tubercles. It has been observed releasing

gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...

s into the

water column The (oceanic) water column is a concept used in oceanography to describe the physical (temperature, salinity, light penetration) and chemical ( pH, dissolved oxygen, nutrient salts) characteristics of seawater at different depths for a defined ...

by standing on the tips of its arms to raise its body off the sea floor. However, little is known of the biology of this starfish.

References

{{Taxonbar, from=Q2189173 Valvatida Animals described in 1911 Echinoderms of the Pacific Ocean