Sand star

Astropecten irregularis

ORDER

Paxillosida

FAMILY Astropectinidae

TAXONOMY

Asterias irregularis Pennant, 1777.

OTHER COMMON NAMES

English: Burrowing starfish.

PHYSICAL CHARACTERISTICS

Varies in size, but commonly between 2 in (5 cm) and 4 in (10 cm), but up to 8 in (20 cm) in deep waters. Pale violet to yellowish color with five relatively short and tapering arms that form stiff and distinct angles. It has well-developed upper and lower marginal plates fringed with small spines. The tube feet are pointed and sucker-less.

DISTRIBUTION

Geographical range extends from Norway to Morocco and found sub-tidally between 16 ft (5 m) and 3,281 ft (1,000 m).

HABITAT

Inhabits a variety of different substratum ranging from coarse gravel to fine mud, although it is more commonly found in sandy substrata. Usually buried either partially or completely within the sediment.

BEHAVIOR

Migrates offshore into deeper water during the winter months to avoid cooling seawater temperatures and being dislodged by strong onshore storm surges. They show quadri-diurnal pattern of locomotory activity that coincide with periods of slack water during high and low tidal cycles, enabling prey buried in sediment to be detected more easily. It has a commensal worm Acholoe squamosa, which freely enters the stomach and lives in the ambulacral grooves.

FEEDING ECOLOGY AND DIET

Intra-oral feeder, prey are excavated from the sediment and swallowed whole. Voracious predators of mollusks, particularly the clam Spisula subtruncata, polychaetes, crustaceans, and other echinoderms. It has a limited olfactory ability and relies on detecting prey by touch.

REPRODUCTIVE BIOLOGY

Sexual reproduction. Spawning occurs between May and July following a rise in seawater temperature. Prior to spawning sea stars aggregate together to reproduce.

CONSERVATION STATUS Not listed by the IUCN.

SIGNIFICANCE TO HUMANS

Arm damage is used as an indicator of bottom trawling impact. ♦

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