Description: This sponge grows as a small thin sheet, typically in patches of only 1-2cm in diameter. The colony usually has a very irregular outline, giving the appearance of several separate patches. The colour of this sponge is a very distinctive bright blue or green. The surface has small pore sieves, similar to Hemimycale columella.

Habitat: This species is most commonly found on lower circalittoral bedrock or boulders in sheltered or moderately exposed sites.

Distribution: Known recently from scattered sites on the south-west, west, and northern coasts of Ireland, and also western Scotland.

Similar Species: The combination of pore sieves and bright blue or green colour seems to be characteristic of this species. Terpios fugax is also a blue encrusting sponge, normally found in the littoral or shallow sublittoral, however this species lacks pore sieves.

Key Identification Features:

• Bright blue or green colour.
• Thin sheet with pore sieves.

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

iNaturalist: Hymedesmia paupertas at iNaturalist World Species Observations database.

WoRMS: Hymedesmia paupertas at World Register of Marine Species. Accepted name: Hymedesmia (Hymedesmia) paupertas (Bowerbank, 1866). AphiaID: 133621.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Poecilosclerida; Hymedesmiidae; Hymedesmia