A burrowing starfish that lives on sands and muddy sands, particularly on Northern Ireland’s eastern coast. It has declined rapidly, probably due to impact from bottom fishing.

In brief

• Can be found off Rathlin, in Strangford Lough, and around the south-east Co. Down coast
• Habitat is sands and muddy sands where it usually buries itself
• Can be seen the year round but probably is more numerous in summer
• Has undergone a rapid decline
• Main threats — bottom fisheries, and disruption of habitat.

Species description: This is a classically shaped starfish, although with a rather flat profile, with five tapering arms. At the edge of each arm there is a double series of marginal plates, each of the upper of these has a long pointed spine. The tube feet are pointed and lack suckers. The upper surface of the starfish has a rather sandy texture, and the whole animal is sandy or pinkish-brown in colour, although the underside is somewhat paler. The arms have purple tips and there is often a purple spot in the centre of the animal on the upper surface. The total diameter is usually 50-150mm, but it may reach 200mm. The starfish feeds on shellfish, crustaceans and worms within the sediment, but may come to the surface at dawn and dusk to feed as well. It can bury itself within about 30 seconds, settling into the sediment vertically. When buried, it maintains surface contact through the tips of its arms.

Life cycle: The population appears to vary seasonally, reaching a maximum in summer, minimum in winter, but this may well be explained by migration of many individuals into deeper water during winter. The high summer densities may represent spawning aggregations or availability of suitable prey. Spawning has been recorded in late spring or early summer, and redevelopment of gonads takes place through the winter and into spring.

Similar species: None in shallow, divable waters.

How to see this species: In Northern Ireland the species can be found in most locations where sublittoral sands or muddy sands occur, and elsewhere it can be found down to 1,000m depth. Recorded sites include off Rathlin Island’s southern coast, in Strangford Lough, off Ardglass, in Dundrum Bay and off the coast from Annalong to the Hellyhunter Rock. Many similar habitats in the Republic of Ireland also support the species, including sites in Donegal, Mayo, Galway, Clare and Cork, as well as the Lambay Deep off Dublin. In Britain it has a primarily westerly distribution, but also occurs off Orkney, Shetland, and in the North Sea.

Current status: Known from a wide range of sites around Northern Ireland, particularly off the east coast. The species has no legal protection.

Why is this species a priority in Northern Ireland? Astropecten irregularis is thought to be declining rapidly in Northern Ireland.

Threats: The habitat of this species is under considerable pressure from the deployment of mobile bottom fishing gear which disrupts the sediments in which it lives, and which probably has an impact on its food species as well.

Action:

• Maintain the number of viable populations of the species
• Maintain the range of the species
• Establish appropriate management on suitable historical sites with a view to targeted recovery
• Monitor the population at key locations.

Objectives: Records of new sites for this species, with details of habitat and population are always valuable. Send these to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257 or e-mail cedar.info [at] nmni.com. If you are a diver, and interested in becoming involved in recording marine life in Northern Ireland through the Seasearch project, contact Claire Goodwin at claire.goodwin [at] gmail.com or look at the web site www.seasearch.org.uk (Northern Ireland web pages).

Conservation: Survey work is being conducted throughout Northern Ireland waters (including the north coast) by Northern Ireland Environment Agency for this and other species and habitats generally.

Rathlin Island and its waters and Strangford Lough have been designated Special Protection Areas under the EU Habitats Directive. Use of mobile fishing gear in Strangford Lough has been banned.

There is no Species Action Plan for Astropecten irregularis, but the relevant UK and NI Habitat Action Plans are Inshore Sublittoral Sediment and Sublittoral Sands and Gravels. The latter for Northern Ireland carries the following targets:

• maintain the extent of a representative range of sublittoral sands and gravel habitats and associated communities in Northern Ireland
• maintain the condition of a representative range of sublittoral sands and gravel habitats and associated communities in Northern Ireland.

It also has the following provision:

Sublittoral sands and gravel beds are used by a large number of Northern Ireland priority species, including the sea cucumber Leptosynapta bergensis, the burrowing anemones Anemonactis mazeli and Edwardsia timida, the sea pen Virgularia mirabilis,the starfish Anseropoda placenta and Astropecten irregularis and the rugose squat lobster Munida rugosa. The requirements of these species should be taken into account during the implementation of this plan.

Distribution Map from NBN: Astropecten irregularis at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Astropecten irregularis at iNaturalist World Species Observations database.

WoRMS: Astropecten irregularis at World Register of Marine Species. Accepted name: Astropecten irregularis (Pennant, 1777). AphiaID: 123867.

Literature:

Christensen, A.M. (1970). Feeding biology of the sea-star Astropecten irregularis Pennant. Ophelia 8: 1-134.

Freeman, S.M., Richardson, C.A. and Seed, R. (2001). Seasonal Abundance, Spatial Distribution, Spawning and Growth of Astropecten irregularis (Echinodermata: Asteroidea). Estuarine, Coastal and Shelf Science 53(1): 39-49.

Picton, B.E. and Morrow, C.C. (2007). [In] Encyclopedia of Marine Life of Britain and Ireland.

http://www.habitas.org.uk/marinelife/species.asp?item=ZB410.

Sabatini, M. (2008). Astropecten irregularis. A sand star. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 02/06/2008]. http://www.marlin.ac.uk/species/Astropectenirregularis.htm.

Classification: Biota; Animalia; Echinodermata; Asterozoa; Asteroidea; Ambuloasteroidea; Neoasteroidea; Valvatacea; Paxillosida; Astropectinidae; Astropecten

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Allen & Mellon Environmental Ltd. (2026). Astropecten irregularis. (Pennant, 1777). [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=ZB410. Accessed on 2026-07-28