''Astropecten polyacanthus'', the sand sifting starfish or comb sea star, is a

sea star 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 ...

of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Astropectinidae The Astropectinidae are a family of sea stars in the order Paxillosida. Usually, these starfish live on the seabed and immerse themselves in soft sediment such as sand and mud. They are not to be confused with species in the genus '' Archaster' ...

. It is the most widespread species in the genus ''Astropecten'', found throughout the

Indo-Pacific The Indo-Pacific is a vast biogeographic region of Earth. In a narrow sense, sometimes known as the Indo-West Pacific or Indo-Pacific Asia, it comprises the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the ...

region. The armspread is up to . The

specific epithet In Taxonomy (biology), taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin gramm ...

"polyacanthus" comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

meaning "many thorned".Astropecten polyacanthus - Comb seastar
JulianRocks.net. Retrieved 2012-04-07.

Description

The upper surface of the comb star is a dark purplish colour, while the underside is orange. On the upper surface paxillae (Latin, "little stakes"), little pillars with flattened summits, are cream, grey or brown, the colours sometimes making a chevron pattern. Along the edges of the five arms there is a fringe of long, sharp marginal spines, usually with brown bases and pale tips. The arms are fairly broad and have a maximum length of . The tube feet are pointed rather than having suckers, an arrangement that is more suitable for digging. ''Astropecten polyacanthus'' can be confused with ''

Archaster Archasteridae is a family of starfish found in shallow waters in the tropical Indo-Pacific region. The genus ''Astropus'', previously included in this family, is now included in the genus ''Archaster'' with the single species, ''Astropus longipes ...

spp.'' which look similar because both have developed features to enable them to dig through sand through

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

. ''Archaster'' has spines that are flat and blunt and on its upper surface has parallel, radial rows of plates while ''Astropecten polyacanthus'' does not.Telling Apart Sand Stars: ''Archaster'' vs. ''Astropecten''! Two Common Trade Species
Echinoblog. Retrieved 2012-04-07.

Distribution

The comb star is found in shallow tropical and sub-tropical seas throughout the

region from the

Red Sea The Red Sea is a sea inlet of the Indian Ocean, lying between Africa and Asia. Its connection to the ocean is in the south, through the Bab-el-Mandeb Strait and the Gulf of Aden. To its north lie the Sinai Peninsula, the Gulf of Aqaba, and th ...

and

Zanzibar Zanzibar is a Tanzanian archipelago off the coast of East Africa. It is located in the Indian Ocean, and consists of many small Island, islands and two large ones: Unguja (the main island, referred to informally as Zanzibar) and Pemba Island. ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, and from

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

. In Australia the range extends from

Cape Naturaliste Cape Naturaliste is a headland in the south western region of Western Australia at the western edge of the Geographe Bay. It is the northernmost point of the Leeuwin-Naturaliste Ridge, which was named after the cape. The Leeuwin-Naturaliste Nat ...

in the west, round the north coast to

Sydney Sydney is the capital city of the States and territories of Australia, state of New South Wales and the List of cities in Australia by population, most populous city in Australia. Located on Australia's east coast, the metropolis surrounds Syd ...

in the east. It is often found on silty sand bottoms in harbours and estuaries.Comb Seastar (''Astropecten polyacanthus'')
Scuba Equipment USA. Retrieved 2012-04-07. It is found at depths down to about .

Biology

The comb star spends much of its time buried in the silty seabed. It feeds on

detritus In biology, detritus ( or ) is organic matter made up of the decomposition, decomposing remains of organisms and plants, and also of feces. Detritus usually hosts communities of microorganisms that colonize and decomposition, decompose (Reminera ...

and

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

and

gastropod Gastropods (), commonly known as slugs and snails, belong to a large Taxonomy (biology), taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and fro ...

molluscs which it swallows whole. It also sometimes engulfs pebbles and digests the biofilm and small invertebrates adhering to the surface. ''Astropecten polyacanthus'' contains the potent

neurotoxin Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2000 that can adversely affect function ...

tetrodotoxin Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an Order (biology), order that includes Tetraodontidae, pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Alt ...

, also known as TTX which has no known antidote. In a case of paralytic poisoning in Japan it was found that the victim had eaten a trumpet shell, ''

Charonia lampas ''Charonia lampas'', common name the pink lady, is a species of predatory sea snail, a marine gastropod mollusk in the family Charoniidae. Distribution This marine species has a wide distribution: the North Sea, the North Atlantic Ocean (Azore ...

'', which had acquired the toxin through its

food chain A food chain is a linear network of links in a food web, often starting with an autotroph (such as grass or algae), also called a producer, and typically ending at an apex predator (such as grizzly bears or killer whales), detritivore (such as ...

, thus implicating ''Astropecten polyacanthus''. In a study that followed this incident, most of the 54 comb stars assayed contained TTX, with one individual having a toxicity score of 520 mouse units per gram.

Use in aquaria

The comb star is sometimes kept in

reef aquaria A reef aquarium or reef tank is a marine aquarium that prominently displays live corals and other marine invertebrates as well as fish that play a role in maintaining the tropical coral reef environment. A reef aquarium requires appropriately in ...

where it is efficient at clearing detritus and uneaten food from the sand or gravel. It is mostly

nocturnal Nocturnality is a ethology, behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnality, diurnal meaning the opposite. Nocturnal creatur ...

and needs to be acclimatized gradually to the conditions in the tank. If it is overstocked, it will starve.''Astropecten polyacanthus'' - Sand Sifting Starfish
Blue Zoo Aquatics. Retrieved 2012-04-07.

References

External links

* {{Taxonbar, from=Q2383575 polyacanthus Echinoderms of New Zealand Starfish described in 1842