(Fabricius, 1780)
Species Overview
Sycon ciliatum (Fabricius, 1780), also known as Scypha ciliata , is a white tubular sponge of which the terminal oscule is crowned by a fringe of long stiff spicules. Tubes are normally a few centimeters in length and are either solitary or occur in small clusters. It is a very common and characteristic shallow-water calcareous sponge occurring along most coasts of Europe, among seaweeds, hydroids and on rocks in the littoral and shallow-sublittoral. From Holland a similar species, Sycon scaldiense , has been described which may be distinguished easily by a much more "hairy" surface.
Taxonomic Description
Colour: Off-white, grey or brown.
Shape, size, surface and consistency: (Sycon ciliatum 2) (Sycon ciliatum Mario) Tubular, usually single, but clusters of separate individuals often occur together, up to 9 cm long (though usually 1-3 cm). Surface usually finely papillate and hairy, though occasionally smooth. If smooth it may be impossible to separate from Grantia compressa . There is a single terminal oscule, which is normally fringed with a crown of spicules. Consistency moderately soft, though can be firmer.
Spicules: (Sycon ciliatum spics) Calcareous. Triactines are localized in various parts of the skeleton, rays 100-200 x 5-10 µm with basal ray varying from 100-250 µm, with larger ones in the choanosomal layer.
Tetractines of the chamber layer are of two types, with apical rays pointing into the ectosome, and with short curved apical rays projecting into the central atrium, ray lengths between 100 and 200 x 5-10 µm with apical rays 20-80 x 8-10 µm.
Oxeas are long and thin, straight, and tapering gradually to pointed extremities, 1000-3000 x 6-25 µm.
Skeleton: (Sycon ciliatum cross) The ectosomal skeleton is a tangential layer of small triactines with long straight oxeas projecting beyond the surface. The skeleton of the chamber layer consists of regularly overlapping tetractines. There is a choanosomal skeleton of larger triactines. A crown of oxeas surrounds the terminal osculum.
Choanocyte chambers: The choanocyte chambers are entirely free from each other, giving the sponge a "loose" consistency.
Reproduction: July-August.
Ecology: Intertidal under overhangs near low water mark. Common in shallow sublittoral, present in deeper water.
Distribution: Arctic to Gibraltar.
Etymology: The name means: provided with hairs.
Type specimen information: No type material in BMNH. MCS Voucher BELUM: Mc7. Strangford Lough, Down.
Remarks
Identifications by eye are usually correct, though beware of the species listed below. Outer surface must be finely papillate (use x10 hand lens). In this species the papillae are the free ends of the water pumping (flagellate) chambers. A similar species sofar reported only from Holland is Sycon scaldiense ; this has a characteristic "hairy" aspect (due to extremely long oxeas protruding from the surface of the sponge).
Confusion is possible with Grantia compressa : Sycon ciliatum is normally finely papillate, but may have a smooth surface and G . compressa is normally flat, but may be cylindrical. There seems to be an overlap in external appearance between these two species. Both are common on most shores, in the same sort of habitats.
Confusion is also possible with Leuconia johnstoni . This species has tubular chimney-like lobes but these are joined by a common base, and there are short rims to the terminal oscules.
Sycon coronatum is a much used name but is here considered a junior synonym of S . ciliatum , following Van Koolwijk (1982). Alleged differences are the thickness of the oxeas and some minor differences in oogenesis and embryology; the latter observations are made from dubiously identified material.
Source: Ackers et al., 1992