Dotted Nudibranch

Jorunna funebris is a large species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusc in the family Discodorididae.

Description

Its oval elongated body is white with round or oval patches containing black papillae. These are spiculose, giving a spiky appearance to the animal. The rhinophores have a translucent stalk and black or brown clavus. The six, black or brown, quite sparsely branched gills form a complete circle around the anus.

The pattern and density of black spicules is variable. The most colour form has the rings occupying about one-quarter of the area of the mantle. Specimens occasionally also occur in which the rings are reduced in size so the mantle is almost pure white, whilst some specimens had the rings on the mantle so large that they virtually coalesced.

In juvenile form the black spots are in fact open rings and as they grow the other apparent spots will also expand in size and become black rings.

Distribution

It is widespread in the Indo-Pacific region from the Red Sea and the Indian Ocean along the East African coast to Australia and New Caledonia.

Habitat

It is found in moderately exposed locations at depth to 18 m. It lays a white spawn mass consisting of a coil of three, loose whorls, being attached by one edge to the sustrate. The ova (170 µm diameter) occur individually within capsules (240 µm). It probably feeds on a slate-blue sponge (Neopetrosia sp.).