(Cuvier, 1804)
Description:
This distinctive and common species may reach 55 mm in length and is soft and velvety to the touch. The ample mantle is covered with small, glistening, uniform, spiculose tubercles of the caryophyllidia type, each of which has a distinctive, retractile, central, finger-like papilla (J. tomentosa). The mantle colour gives good camouflage while on or near encrusting sponges; it is sandy brown, yellow, orange or grey-white. A fairly constant feature is the presence of an approximately paired series of dark brown blotches down the sides of the dorsum. Specimens from the west of Ireland may lack these spots (the variety lemchei ). The margins of the rhinophore pits are slightly raised and crenulated. There are up to seventeen tripinnate gills; the gill pocket, when the gills are fully extended, is elevated and forms a short, cylindrical, vase-like base for the gill circlet. The head bears slender, digitiform oral tentacles. The propodium is bilaminate, the anterior lamina notched in the midline (J. tomentosa-photo).
Habitat:
On British shores, this species feeds chiefly upon the encrusting siliceous sponges Halichondria panacea and Haliclona spp. , to 400 m.
Distribution:
This species is common from Norway to the Mediterranean Sea (Adriatic) (Distr. J. tomentosa).