A large deep-water sponge that has been found only on Rathlin Island within depths normally accessible to divers. It is not known whether there are any threats to the population.

In brief

• Found off Farganlack Point, Rathlin Island
• Habitat is boulders and bedrock
• Can be found throughout the year
• Listed as an SOCC on account of its extreme rarity
• Main threats / cause of decline if any, not known.

Species description: This is a very large sponge, growing up to 30cm in height, a dull grey or pale buff colour. On occasion, it assumes an erect form whereby it broadens out from a narrower base. It is irregular but rounded and often a roughly triangular shape. To the touch it is compressible, but tough and fibrous and has grooves running irregularly over the surface. The pores (oscules) of diameter about 5mm are located on low transparent cones on the surface. Spicules (skeletal structures) are long and needle-shaped - others seen by microscope somewhat resemble the mouthpiece of a telephone.

Life cycle: Sponges have either separate sexes or are hermaphrodite. In the case of the latter, self-fertilisation is avoided by eggs and sperms maturing at different rates within the same individual, so when spawning takes place and sperms are released through exhalent openings, it is unlikely that the eggs will be fertilised. Alternatively the eggs are retained within the sponge, and sperms drawn in from surrounding water. Fertilised eggs are released and develop into planktonic larvae. Asexual reproduction may also be achieved by budding, whereby a small unit of the sponge separates and develops as an independent entity.

Similar species: This is a distinctive sponge, but it has two synonyms: Esperia placoides, and Esperella murrayi.

How to see this species: The species has a worldwide distribution, occurring in deep waters round to Australia; in the north Atlantic it is found from the Azores to Spitzbergen, and into the Mediterranean. The only Northern Ireland location with divable depths is off Farganlack Point on the north coast of Rathlin Island, but it is also found at a number of locations off western Scotland, as well as Brittany, and the Faeroes. It occurs on bedrock and boulders in depths from 30-2460m.

Current status: Rare in Northern Ireland, and the Rathlin site is the only one recorded in all Ireland. The species has no legal protection.

Why is this species a priority in Northern Ireland? Listed as a Species of Conservation Concern on account of its extreme rarity in Northern Ireland and Ireland as a whole.

Threats: There is insufficient information to determine if the species is declining, and if so, what the likely causes might be.

Action:

• Maintain the only known site of the species on Rathlin Island and monitor its population
• Maintain the range of the species
• Document and appropriately manage any new 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 has been designated a Special Area for Conservation under the EU Habitats Directive.

There is no Species Action Plan for Mycale lingua, but the UK Habitat Action Plan for Inshore Sublittoral Rock has the following objectives:

• maintain the extent and quality of inshore sublittoral rock habitats in the UK, including the full diversity of communities.

Measures to be considered further include:

• protecting sites of conservation importance from damage through contamination and physical disturbance (for example, turbidity and towed fishing gear)
• requiring EIAs for coastal developments to examine potential effects on intertidal and nearshore areas
• monitoring any impact of dump sites on inshore sublittoral rock habitats, communities and wildlife, and taking action as appropriate
• implementing strategies for managing the coastal zone at local, regional and national levels.

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

iNaturalist: Mycale lingua at iNaturalist World Species Observations database.

WoRMS: Mycale lingua at World Register of Marine Species. Accepted name: Mycale (Mycale) lingua (Bowerbank, 1866). AphiaID: 168640.

Literature:

Picton, B.E., Morrow, C.C. and van Soest, R.W.B. (2007). [In] Sponges of Britain and Ireland. http://www.habitas.org.uk/marinelife/sponges.asp?item=C5440.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Poecilosclerida; Mycalidae; Mycale

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Allen & Mellon Environmental Ltd. (2026). Mycale lingua. (Bowerbank, 1866). [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=C5440. Accessed on 2026-07-28