Thecacera pennigera

(Montagu, 1815)

This species may reach 30 mm in length, with a ground colour of white, and numerous irregularly shaped orange blotches and jet-black and yellow spots over the dorsum. The black spots are always smaller than the orange areas. The rhinophores issue from complex sheaths which are open mesially and rise to form massive clubs behind. There are 3-5 bipinnate or tripinnate gills, white with orange and black spots, and behind the gills is a pair of club-like, dorso-lateral, glandular, defensive ceratal processes. The front of the foot is produced into antero-lateral points, the propodial tentacles. No oral tentacles are present (Thecacera pennigera) (Thecacera with eggs).

This species feeds upon the bryozoan Bugula spp. It is always found in shallow water, to 20 m, and it seems probable that its distribution has been assisted by shipping, like its prey.

Only in the southern North Sea (Distr. T. pennigera). Further distribution from Arcachon and the Mediterranean Sea (as far as Sicily), Brazil, South Africa, Pakistan, Australia, Japan and New Zealand.