Form: Thinly encrusting sheet of 3 cm in diameter, 1-3 mm in thickness.
Consistency: Firm, fairly tough, thin sheet.
Surface: Surface partly translucent, with broad excurrent channels.
Apertures: Surface is covered with pore-sieves (cribri) with raised rims, these close on disturbance. Oscules are fairly large, with raised rims.
Contraction: Oscules and cribri close on disturbance.
Skeleton: The ectosomal spicules form thick bundles, arranged tangentially; there are large quantities of microscleres at the surface. The main skeleton consists of a network of large acanthostyles lying usually 3 or 4 together, sparingly echinated by small acanthostyles. A small quantity of spongin is present.
Spicules: Megascleres : The ectosomal spicules are strongyles, with rather unequal ends, one end being slightly thicker than the other; the shaft is often a little crooked; size is 400-500 x 6 μm. Large acanthostyles have a slightly curved shaft; the head is swollen and is covered with short, blunt spines. A few spines are sometimes scattered along the shaft for a short distance; on the other hand, some of the spicules are almost quite smooth; these spicules measure about 660-950 x 15-21 μm. The echinating acanthostyles are small and few in number; the shaft is straight, the head is a little swollen and is covered with rather long spines; the shaft is thickly set with small, recurved spines; size is 100-140 x 10 μm. Microscleres : Arcuate isochelae; the shaft is fairly strongly curved; it is about 10 μm in breadth in front view; the teeth are rather short; the chelae measure 45-60 μm.
Habitat: Usually on bedrock in sites exposed to deep swell or strong tidal streams on the open coast.
Distribution: A scarce species in Northern Ireland (Maidens, Rathlin Island). Occasional in depths of 30-50m on limestone bedrock off the Aran Islands, Co Galway, Ireland.
Identity: Initial impression is of a sponge similar to Hemimycale columella or Phorbas fictitius but yellow in colour. The spiculation, especially the long, almost smooth, acanthostyles is distinctive. Ectyodoryx atlanticus Stephens, 1921 was described from deep water off the west coast of Ireland. It is similar to this species, but has slightly larger chelae with broader shafts, and more spines on the heads of the long acanthostyles. The large acanthostyles are longer, to 950 μm and the ectosomal spicules are longer, 400-500 μm.
Editors: Claire Goodwin & Bernard Picton
|Picton, B.E., Morrow, C.C. & van Soest, R.W.B., 2011. [In] Sponges of Britain and Ireland |
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