Timea stellata

(Bowerbank, 1866)

Species Overview

Timea stellata (Bowerbank, 1866) is a thinly encrusting bright yellow sponge with a hispid surface. For a certain identification microscopical examination of the microscleres is necessary. It occurs mostly in deeper water in cryptic habitats, but apparently is not rare. It is recorded from the west coasts of the British Isles, France and Spain, down into the Mediterranean.

Taxonomic Description

Colour: Bright yellow to whitish alive, pale or straw yellow in dry condition.
Shape, size, surface and consistency: Thinly encrusting. Up to 1 cm in diameter. Hispid surface. Oscules very small, not visible in preserved specimens.
Spicules: Megascleres : Tylostyles, variable in size, with distinct tyle, which is often trilobate, occasionally ovoid: 170-1000+ x 1-15 µm.
Microscleres : Strongylasters or chiasters, without a distinct centre, with 6-8 cylindrical rays which are mostly lightly spined, occasionally smooth, spines with truncate heavily spined ends: 13-25 µm.
Skeleton: Tylostyles are erect on the substrate, either singly or in groups, heads down; the largest stick far beyond the ectosome, forming the surface spination. Microscleres numerous throughout the sponge, but especially concentrated at the surface.
Ecology: Encrusting the undersides of stones and shells, from 15 m downwards.
Distribution: Shetland Isles, Straits of Dover, Guernsey, Roscoff, NW Spain; Mediterranean.
Etymology: The name refers to the presence of asters.
Type specimen information: The type is in the Natural History Museum, London.

Remarks

This is the commonest and most widespread of the Timea species of the area. Its asters are clearly different from the others in being simple, 6-8 rayed, strongylasters.
Source: Topsent, 1900