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Schmidt, 1862

Species Overview

Sycon raphanus Schmidt (1862) is an oval or globular tube-shaped calcareous sponge with a hairy surface. It is similar to S. ciliatum but differs in having choanocyte chambers fused over much of their length (histological preparation necessary).

Taxonomic Description

Colour: White, grey or yellow.
Shape, size, surface and consistency: Globular to fusiform, with a terminal oscule surrounded by a fringe of stiff spicules. Height up to 8 cm, diameter up to 2.7 cm; may occasionally have a short stalk. Surface hairy or hispid. Consistency soft.
Spicules: (Sycon raphanus spics) Calcareous. Triactines: rays 100-250 x 8-12. Tetractines of the atrial skeleton: similar to triactines, with apical rays of 60-120 µm.
Oxeas: 1000-3000 x 20-24 µm.
Skeleton: Tubar skeleton of triactines with distal cones with brushes of oxeas; atrial skeleton of triactines and tetractines.
Choanocyte chambers: Fused over almost their entire length, excepting the distal cones.
Reproduction: August.
Ecology: Intertidal caves and among weeds in rock pools in exposed habitats; under stones in the littoral; on vertical cliffs; sublittoral down to 70 m.
Distribution: Norway, Faroes, W Ireland, Roscoff, Iles de Glénan, Galicia; Mediterranean.
Etymology: raphanus (Greek) = radish, presumably referring to the shape of the sponge.
Type specimen information: The types are in the Natural History Museum, London, BMNH 1867:7:26:5 (cotype-wet) and BMNH 1867:3:11:75 (Schmidt slide).

Remarks

This is very similar to Sycon ciliatum in spiculation, but a major difference is found in the degree of fusion of the choanocyte chambers (radial tubes). In S. raphanus these are almost entirely fused just up to the distal cone, whereas in S. ciliatum the choanocyte chambers are entirely free from each other.
Source: Arndt, 1935

Sycon raphanus