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''Astropecten irregularis'' 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
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' ...
. Common names include Sand sea star (A. i. pontoporeus).Jones, Georgina. ''A field guide to the marine animals of the Cape Peninsula.'' SURG, Cape Town, 2008.


Habitat and behaviour

Starfishes of genus Astropecten live on mobile seabed (sandy, muddy or gravel seabed), and they remain largely buried under sediment during the day. During the late afternoon and the night, starfish go out to hunt mainly bivalve molluscs, which are their favourite prey. ''Astropecten irregularis'' is a very common species in all kind of mobile seabed from 1 to about 1,000 m deep. This species is active and easy to find during the night, sometimes it is possible to find it in the late afternoon.


Description

This species lives in the Atlantic Ocean and in the Mediterranean, but the two populations show differences in superomarginal plates. In particular, the specimens of the Mediterranean have superomarginal plates devoid of spines (they are considered by some author as the subspecies Astropecten irregularis pentacanthus) while Atlantic populations are provided with one spine for each superomarginal plates (they are considered by some authors as the subspecies Astropecten irregularis irregularis) or more spines (they are considered by some authors as the subspecies Astropecten irregularis serratus and by some others as a variety of Astropecten irregularis irregularis). This starfish has a well-developed and raised superomarginal plates and the specimens in the Mediterranean are totally devoid of spines. The inferomarginal plates are short, thin, fine-spines, highly mobile and white colour. Astropecten irregularis doesn’t keep these spines rigid and parallel to each other as the other species do. The
arms Arms or ARMS may refer to: *Arm or arms, the upper limbs of the body Arm, Arms, or ARMS may also refer to: People * Ida A. T. Arms (1856–1931), American missionary-educator, temperance leader Coat of arms or weapons *Armaments or weapons **Fi ...
make up among them, at their base where they join the disc, a very clean corner. The colour of aboral side is pink homogeneous, often violet in towards the end of the arms and sometimes there are many small darker spots in the central disc. Sometimes it has a bulge on centre of the disc that is highly developed in this species. This bulge protrudes from the sediment where the animal is hidden and it has respiratory functions (called "aboral-cone”). Usually it has diameter of about 10–12 cm with a maximum of 19 cm. It's a very common species in all kind of mobile seabed from 1 to about 1,000 m deep. Usually this starfish can be distinguished easily and safely from the others species of Mediterranean for superomarginal plates devoid of spines and from colour. Sometimes it is confused with Astropecten aranciacus for the similar colour, but it’s always possible to distinguish the two species by a closer inspection of superomarginal plates and inferomarginal spines or by observations of the colour of the paxillae.


Feeding

This sea star is a
carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...
and feeds on
mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...
s, which it catches with its arms and then takes to the mouth. The prey is then trapped by the long, moving prickles around the mouth cavity.


Synonymised taxa

*''Asterias aranciaca'' O.F. Mueller, 1776 (Synonym according to Sladen (1889))Mah, C.; Hansson, H. (2013). Astropecten irregularis (Pennant, 1777). In: Mah, C.L. (2013). World Asteroidea database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=123867 on 2013-09-18 *''Astropecten acicularis'' Norman, 1865 (synonym according to Sladen (1889)) *''Astropecten aurantiaca'' Forbes, 1841 (synonym according to Perrier (1875)) *''Astropecten hispidus'' Müller & Troschel, 1842 (synonym according to Doderlein (1917)) *''Astropecten muelleri'' Müller & Troschel, 1844 (synonym) *''Astropecten muelleri'' Düben, 1845 (Synonym according to Doderlein (1917)) *''Astropecten pontoporeus'' Sladen, 1883 (Subspecies according to Doderlein (1917))


Subspecies

*''Astropecten irregularis irregularis'' (Pennant, 1777) *''Astropecten irregularis pentacanthus'' (Delle Chiaje, 1827) *''Astropecten irregularis pontoporeus'' Sladen, 1883 *''Astropecten irregularis serratus'' (Müller & Troschel, 1842)


References


Roberto Pillon (2009). Astropecten of the Mediterranean Sea
* Koehler, Réné. 1921. ''Faune de France. Echinodermes''. * Tortonese, Enrico. 1965. ''Fauna d'Italia. Echinodermata''. * Ludwig, Hubert. 1897. ''Die Seesterne des Mittelmeeres. Zoologischen station zu Neapel''.


External links


Downloadable WoRMS: Roberto Pillon (2009). Astropecten of the Mediterranean Sea

Downloadable WoRMS: Roberto Pillon (2009). Orientarsi in un mare di stelle

DORIS

WoRMS

SeaLifeBase

Naturamediterraneo

MarLIN

Encyclopedia of Marine Life of Britain and Ireland



Mer et littoral
{{Taxonbar, from=Q1749115 irregularis Starfish described in 1777 Echinoderms of the Atlantic Ocean Fauna of the Mediterranean Sea