Form: Very variable. Thin sheets may have thin tassel-like outgrowths reminiscent of Halichondria bowerbanki, but are thinner. Encrusting forms resemble Haliclona viscosa or Halichondria cinerea, with lobate growths each with oscules. Tassel-like forms similar to Iophon nigricans have been observed in sheltered conditions.
Colour: Greyish beige, with a tinge of pink or purple.
Consistency: Very soft, compressible.
Surface: Smooth or rugose, or smoothly lobate, with a porous appearance similar to that of Haliclona viscosa.
Apertures: These may be the most constant feature of the external appearance of this species. The oscules have a raised transparent rim with a few converging transparent excurrent canals. The oscular rims may develop short tassels reminiscent of Amphilectus fucorum (q.v.). However, in thinly encrusting specimens the oscules may not be apparent.
Contraction: Oscules become inconspicuous on collection.
Skeleton: Slender styles often forming wisp-like bundles running towards the surface; otherwise somewhat irregularly arranged.
Spicules: Slender styles, often flexuous, typically ca. 220μm x 3-6μm. According to Burton, distal ends narrow to a point in semi-discrete steps - this feature is not visible in all specimens, and occurs in only about 10% of spicules in most specimens.
Habitat: On rock, algae, bryozoans such as Cellaria and Pentapora, etc, in sites sheltered from wave action, but with moderate tidal streams. Infralittoral.
Distribution: Recently reported from Shetland, W. coast of Scotland, Ireland, probably not uncommon. The type locality is Kyle Scotnish, Loch Sween, Scotland. 56 01.365'N 005 37.161'W. Depth 15-30cm below LWST.
Distribution Map: NBN map : National Biodiversity Network mapping facility, data for UK.
Identity: Very thin styles (with distinctive narrowing to the point), together with soft texture, lack of microscleres or other types of megascleres, and halichondroid skeleton, are the best distinguishing features.
Voucher: BELUM : Mc617. Ard Bay, Galway.
Editors: D. Moss, B.E. Picton.
|Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland |
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