Form: Very thin sheet, almost impossible to remove from the substratum except in tiny pieces.

Colour: Typically orange/red.

Smell: None.

Consistency: Too thin to determine.

Surface: Usually silt covered with regularly spaced red raised bumps showing through, occasionally clean with these raised bumps. Villose, due to scattered long spicules which penetrate the surface.

Apertures:

• The oscules are small, at the summits of the raised bumps mentioned above. No ostia visible.

Contraction:

• None, difficult to determine.

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Internal characters

Skeleton: The skeleton consists of a basal layer of short, stout tylostyles with distinctive outer ends consisting of a ball of spines, mixed with scattered long tylostyles which penetrate the surface. Where the latter penetrate the surface there is a brush of fine styles. (see skeletal drawing for Eurypon major.)

Spicules: Three categories of megasclere and no microscleres are present. The largest megascleres are long tylostyles with rounded heads and smooth shafts. Shorter tylostyles with distinctive spined ends and flask-shaped rounded heads are abundant. Fine, thin styles are freqent, forming brushes at surface.

Identity: The short spicules with spined ends are very distinctive and are not found in any other British species. In the field the thin red sheet, often silt-covered, is difficult to distinguish from some Eurypon species, but it is even thinner than most of these.

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

iNaturalist: Hymeraphia stellifera at iNaturalist World Species Observations database.

WoRMS: Hymeraphia stellifera at World Register of Marine Species. Accepted name: Hymeraphia stellifera Bowerbank, 1864. AphiaID: 133133.

Classification: Biota; Animalia; Porifera; Demospongiae; Heteroscleromorpha; Axinellida; Raspailiidae; Raspailiinae; Hymeraphia

Editors: B.E. Picton