(Schmidt, 1869)
Species Overview
Sycandra utriculus (Schmidt, 1869) is a large flattened, thin-walled sac shaped sponge with a beige colour. It hangs down from its point of attachment. It has a distal terminal "naked" oscule. Despite it being a calcareous sponge it feels smooth-velvety. A rare northern species.
Taxonomic Description
Colour: Beige (alive or in alcohol).
Shape, size, surface and consistency: (Sycandra utriculus 2) Variable, often basically a thin walled, laterally compressed cylindrical or pear-shaped bag (the walls are thicker and almost muscular in comparison with Grantia compressa ). "Thin" is used relative to the overall size of the sponge—the walls are thick when compared to those of Grantia compressa . It hangs from the point of attachment (Note orientation in photographs). It can grow from 12-15 cm long, the largest specimens seen being 5 cm diameter and in excess of 1 m long. There is also a more lobate form. There is a very short stalk. Surface smooth, slightly velvety. Apertures usually a single terminal oscule, which is naked (i.e. with no collar of spicules). Consistency firm but thin-walled. Contraction: will deflate, but no overall shrinkage.
Spicules: Calcareous. Triactines with rays: 100-200 µm; tetractines with rays: 150-200 µm; oxeas ca. 500 µm.
Skeleton: Essentially as in Grantia compressa : a tangential layer of triactines; the chamber layer consists of overlapping triactines; the choanosomal skeleton has a tangential layer of tetractines.
Ecology: Only recently known from two sites, in each case on vertical or overhung side of wreck in 5-20m. No current. Shallow site was exposed to moderate occasional swell.
Distribution: A northern Atlantic species. Recently found in Orkney on Scapa Flow block ships. Probably reaching southern limit off Northern Scotland. Earlier recorded from Shetland and Faeroes.
Etymology: Utriculus (Latin) = leather bag, referring to the shape of the sponge.
Type specimen information: No type material in BMNH. MCS voucher BELUM: Mc2127. Churchill causeway, Orklley. Coll. D. Moss.
Remarks
The large specimens are unusually large for Calcarea and larger bag-like "Grantia" forms in UK waters are likely to be this species. Smaller specimens could be confused with G . compressa .
Source: Ackers et al., 1992 (D. Moss, S.M. Stone).