Lissodendoryx jenjonesae is a yellow encrusting sponge which is found in deep clear water at sites on Rathlin Island, the Maidens and the west coast of Ireland.

In brief

• Found on Rathlin Island and the Maidens, off Larne.
• Lives on steep or vertical rock faces in water of 25 m or greater depth in moderate to strong tidal streams.
• Not seasonal, this sponge probably remains in one place for many years.
• Northern Ireland is a stronghold for this species.
• Requires rock reef or stable boulder habitats in clean water with a minimum of turbidity.

Species description: This sponge forms cushions which are typically 6 mm thick by 2-5 cm in extent. The surface is covered with conspicuous circular pore sieves and there are a few scattered oscules. It is pale to bright yellow in colour. The spiculation is distinctive and includes unusual long curved acanthostyles which are mostly smooth but with sparsely spined heads.

Life cycle: Reproduction is by swimming larvae which must find suitable substratum to settle on. Settlement in suitable water conditions and initial growth are probably when most mortality occurs due both to chance and to competition for space.

Similar species: There are a number of yellow encrusting sponges in our area but the pore sieves and thickness make this species tentatively identifiable in situ. The first impression is of a yellow form of Hemimycale columella.

How to see this species: Found on steep rock faces in the circalittoral zone, usually in places where there are many other encrusting sponges. Its bright yellow coloration makes this species conspicuous but it has no clear features which can be used to identify it in situ without significant experience, and usually requires microscopic examination of its spicules for confirmation.

Current status: Rare. This species has been found regularly at Rathlin Island and the Maidens, off Larne. There are older records from the Maidens in 1983-89 and an unconfirmed record from the west coast of Ireland. Northern Ireland is considered to be a stronghold for this species as it holds more than 50% of the records worldwide. Like many encrusting sponges this could be partly due to the lack of sampling but the North Channel and Irish Sea do have sponge-rich habitats which are rare and not found elsewhere.

Why is this species a priority in Northern Ireland?

• Criterion 3: Rare or restricted range – rare breeding species confined to 5 hectads or less (based on expert judgement).
• Criterion 4: NI stronghold or endemic – both stronghold range/population and designation as ‘endemic’ subject to expert judgement.

Threats:

• The main threat to this species is degradation of water quality due to increased turbidity, pollution or nutrient enrichment. Inorganic silt clogs sponges making them unable to filter feed and such silt is artificially suspended into the water column by bottom-fishing activities. Some species of sponge can actively clean their surfaces to some extent and may become competitively able to displace other species if there is a shift in water quality.
• Polluted water may cause sponges to become diseased and may benefit some species at the expense of others by providing more bacteria and less plankton as food.
• Nutrient enrichment may have similar effects by changing the amounts of different types of plankton on which the sponges feed.

Action: Records of new sites for this species, with details of habitat and population are always valuable. Observations with a photograph can be recorded using iNaturalist, find the MBDP-NI iNaturalist project here.

Alternatively, records can be sent to CEDaR, National Museums Northern Ireland, 153 Bangor Road, Cultra, Holywood, County Down, BT18 0EU. Tel 028 9039 5257, e-mail cedar.records@nationalmuseumsni.org, or via the online portal.

Objectives:

• Maintain the number of viable populations of the species.
• Maintain the current range of this species.
• Establish appropriate management on appropriate historic sites.
• Encourage sustainable use of the seas by avoiding consumption of fish and shellfish captured by bottom dredging and bottom trawling.

Conservation:

• Rathlin Island is a Marine Protected Area with multiple designations.
• There is Habitat Action Plan for Fragile Sponge and Anthozoan Communities on Rocky Habitats.
• The Maidens are a Marine Protected Area with multiple designations.

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

iNaturalist: Lissodendoryx jenjonesae at iNaturalist World Species Observations database.

WoRMS: Lissodendoryx jenjonesae at World Register of Marine Species. Accepted name: Lissodendoryx (Ectyodoryx) jenjonesae Picton & Goodwin, 2007. AphiaID: 255165.

Literature:

Picton, B.E. and Goodwin, C.E. (2007). Sponges of Rathlin Island. Journal of the Marine Biological Association of the United Kingdom. 87(6): 1441-1458.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Poecilosclerida; Coelosphaeridae; Lissodendoryx

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Picton, B.E., Keatley, L. & Morrow, C.C. (2026). Lissodendoryx jenjonesae. Picton & Goodwin, 2007. [In] Priority species, Marine Biodiversity Portal NI. https://www2.habitas.org.uk/marbiop-ni/priorityaccounts.php?item=C6625. Accessed on 2026-09-13