Form: In the British Isles this species typically assumes a hollow, contractile, massive-fig shape, attached by a stalk to the substrate. On the Continent a variety of forms have been recognized, graduating from thin sheets and cushions to massive-lobose and even branching forms (see Topsent, 1900, p.233). These forms have yet to be found in British waters and may not be conspecific.

Colour: Various shades of pale yellow, buff, pale orange and brown.

Smell: Smells faintly of freshly cut Laminaria stipe.

Consistency: Firm and moderately elastic when out of water. Extremely soft when fully expanded under water. Stalk breaks when bent through 20 deg. (when in contracted condition.)

Surface: Smooth, even with a minutely velvety feel. This is most easily detected with the tongue. The upper surface is often lightly coated with silt.

Apertures:

• Usually one oscule, at the top, but there may be more. If so, they are usually all on the uppermost surface.

Contraction:

• Very dramatic, contracts to about 1/4 of its fully expanded size when disturbed. Full contraction takes about 15 seconds. Further contraction occurs when the sponge is removed from the water.

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Synonyms: (Note Suberites (Hymeniacidon) crustula (Bowerbank, 1866:185) is really Polymastia mamillaris)

Internal characters

Skeleton: Subradiate, the radial arrangement of the spicules being most apparent near the surface. Internally the skeleton is confused, almost halichondroid. There is one type of spicule (tylostyle), of two distinct sizes. The larger (a) constitute the main structural megascleres, whereas the smaller (b) are perpendicularly arranged as plumose brushes (resembling shaving brushes) at the surface. In the stalk region the spicules are condensed to form an axial skeleton.

Spicules: Tylostyles, (a,b) long and thin 330-(410)-500 μm, with typical neat suberitid swellings at the head, like pins. In any given specimen spicules are of a narrower size range than Suberites ficus (q.v). No microscleres.

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

iNaturalist: Suberites carnosus at iNaturalist World Species Observations database.

WoRMS: Suberites carnosus at World Register of Marine Species. Accepted name: Suberites carnosus (Johnston, 1842). AphiaID: 134275.

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

Voucher: BELUM : Mc27. Strangford Lough, Down.

Editors: D. Moss, B.E. Picton.