A very distinctive anemone occurring at a number of sites in County Antrim and in Strangford Lough, comprising the majority of recorded sites in Ireland. Its habitat of sands, gravels and maerl is vulnerable to disturbance from fisheries and aggregate extraction.

In brief

• Found off Rathlin Island, mainland County Antrim, and off reefs in the inner parts of Strangford Lough
• Occurring in sands, gravels and maerl
• Best time to see — year round
• Northern Ireland holds the majority of the recorded sites in Ireland
• Main threats come from use of mobile fishing gear; aggregate extraction could become a problem in future.

Species description: This is a large and very distinctive sea anemone, with a base some 70-90mm in diameter, and broader than the relatively short column, thus giving the animal a bell-like shape. The column has an upper collar, and within that, some 150 very short tentacles arranged in four concentric rings, each terminating in a knob. Colour varies from bright red (most common), yellow or purplish, whilst the central disc and tentacles are sometimes grey, white or brownish, and can be quite blotchy in appearance. When disturbed by nearby movements or disruption of sediments, the animal can rapidly retract its disc and tentacles. The tentacles have relatively few stinging or adhesive cells (nematocysts), and food particles are taken in by everting the throat.

Life cycle: There is currently no information on the life cycle of this species in Northern Ireland or adjacent waters.

Similar species: No other species has the characteristic array of very short tentacles.

How to see this species: Aurelina heterocera can be found embedded in sands, gravels and maerl, most generally subtidally to depths of 600m, and occasionally in lower shores holding this type of substrate. In Northern Ireland it occurs at a number of sites; Church Bay Rathlin, Red Bay, off the Maidens, Gobbins, and in Strangford Lough at Bird Island Passage, off Pawle Island, Colin Rock, Limestone Rock. Only two other locations are recorded in Ireland, namely St John’s Point, Donegal and Kilkieran Bay, Galway. In Britain it is found off western Scotland and Hebrides, Calf of Man, Pembrokeshire, southern England; further afield its range includes European coasts of the Atlantic and Mediterranean.

Current status: In Northern Ireland this species is known from only four locations on the Antrim coast, and four within Strangford Lough, and these represent the majority of the Irish records. It has no legal protection.

Why is this species a priority in Northern Ireland? It is recorded as scarce and declining, with Northern Ireland holding over 50 per cent of the Irish population, and possibly as much as 20 per cent of the UK population.

Threats: Because of its predominantly southern distribution relative to Northern Ireland, there may be some possibility that the species may extend its range northwards if sea temperatures continue to increase. However, the present population is threatened by the vulnerability of its habitat. Sands, gravels and maerl beds can be heavily impacted by mobile bottom fishing gear, resulting in loss of longer-lived species with slower rates of reproduction. Extraction of aggregates for the building industry would pose a similar threat.

Action:

• Maintain the number of viable populations of the species in Northern Ireland
• Maintain the range of the species in a Northern Ireland and all-Ireland context
• Establish appropriate management of known sites.

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 Strangford Lough are designated Special Areas of Conservation under the EU Habitats Directive, and Strangford Lough is a Marine Nature Reserve.

There are no UK or Northern Ireland Species Action Plans for Aurelina heterocera. Relevant Habitat Action Plans are NI and UK plans for Maerl Beds, for Sublittoral Sands and Gravels, Inshore Sublittoral Sediment and Littoral Sediment. The Northern Ireland plan for Sublittoral Sands and Gravels has the following actions:

• 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.

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

iNaturalist: Capnea sanguinea at iNaturalist World Species Observations database.

WoRMS: Capnea sanguinea at World Register of Marine Species. Accepted name: Capnea sanguinea Forbes, 1841. AphiaID: 410805.

Literature:

Rowley, S.J. (2008). Aureliania heterocera. Imperial anemone. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 13/05/2008]. http://www.marlin.ac.uk/species/Aurelianiaheterocera.htm.

Classification: Biota; Animalia; Cnidaria; Anthozoa; Hexacorallia; Actiniaria; Enthemonae; Actinostoloidea; Capneidae; Capnea