(Montagu, 1818)
Species Overview
Raspailia hispida (Montagu, 1818) is a thinly branching-erect, ochre or pale brown, hairy sponge. It resembles Stelligera stuposa but differs in having "hairs" of uniform length and lacking any slime. It is a common species along the rocky west coasts of the British Isles, France and the Iberian Peninsula, occurring in the deeper sublittoral together with other branching erect sponges.
Taxonomic Description
Colour: Ochre, yellow/brown.
Shape, size, surface and consistency: (Raspailia hispida MCS2) (Raspailia hispida V) Branching erect, branch diameter about 4-6 mm, and more or less circular in cross-section. Branches gradually taper to blunt tips. Branching may be very regular and dichotomous; or profusely branched (usually when found in estuarine conditions). Stalked, branchcs rarely fuse. Surface bristly (villose), with hairs of uniform length. Hairs may trap particles of silt. The small oscules can be seen under water, and tend to form evenly spaced rows along the edge of branches; not apparent when preserved. No noticeable slime. Consistency firm, elastic. There is a soft outer layer on a dense axial core. The outer layer is easily rubbed from the inner core.
Spicules: (Raspailia hispida spics) The megascleres of the axial and extra-axial skeletons are styles or subtylostyles 1375-1800 µm. The echinating spicules are acanthostyles 70-135 (rarely acanthoxeas), and are best seen in longitudinal sections (they are rare or very rare in this species). Divergent brushes are of slender styloids (anisoxeas) 220-420 µm.
Skeleton: Plumoreticulate, with a dense axial condensation of reticulating spongin fibres, which are cored by subtylostyles and sparsely echinated by acanthostyles. There is a soft, extra-axial skeleton of long spicules radiating out at right angles from the core to pierce the surface. Divergent brushes of slender spicules surround the projecting spicules at the surface. The spongin becomes more abundant as the animal ages.
Associations: The surface brushes of spicules trap small particulate matter in which worms abound.
Ecology: In moderately exposed sites or sheltered sites with some tidal flow. Often with Raspailia ramosa , Stelligera stuposa and branching erect Axinellids in open water.
Distribution: Widespread along the west and south coasts of the British Isles, France, Spain, Portugal; Mediterranean.
Type specimen information: No type material in BMNH. MCS voucher BELUM Mc809, Portrush, N Ireland.
Remarks
Can be very similar to some individuals of Stelligera stuposa , especially in the middle size range (i.e. up to ca. 15 cm high). A microscopic examination is always essential for positive identification as there is a considerable overlap between the two species. The only characters which may prove to be reliable are the bristly nature of the surface—evenly bristly in Raspailia , unevenly bristly in Stelligera—and that Raspailia does not produce slime whereas Stelligera does. Raspailia tends to accumulate small particles of silt, whereas Stelligera tends to bind the silt into larger particles, probably because of the slime production.
Source: Ackers et al., 1992 (B. E. Picton, S.M. Stone).