Description: This sponge forms very thin vivid dark blue encrustations. Oscules are not usually apparent, they are small and mostly scattered around the edges of the sponge.

Habitat: Frequently found beneath boulders in rapids and areas of strong water movement, both on shore and in shallow water.

Distribution: Fairly common on the south coast of England and in south Wales, scarce elsewhere but found on western and Irish Sea coasts as far north as Scotland.

Similar Species: The only other blue sponge likely to be encountered in the British Isles is Hymedesmia paupertas. This is sublittoral and has conspicuous pore-sieves.

Key Identification Features:

• Vivid dark blue sponge
• Very thin encrustation beneath boulders and in caves

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

iNaturalist: Terpios gelatinosa at iNaturalist World Species Observations database.

WoRMS: Terpios gelatinosa at World Register of Marine Species. Accepted name: Terpios gelatinosus (Bowerbank, 1866). AphiaID: 1041930.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Suberitida; Suberitidae; Terpios