| Thecacera pennigera | |
|---|---|
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Gastropoda |
| Order: | Nudibranchia |
| Family: | Polyceridae |
| Genus: | Thecacera |
| Species: | T. pennigera |
| Binomial name | |
| Thecacera pennigera (Montagu, 1815)[1] |
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| Synonyms[1] | |
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Thecacera pennigera, the winged Thecacara, is a species of sea slug, a shell-less gastropod mollusc in the family Polyceridae.
Contents |
Thecacera pennigera has a short, wide head with two lateral flaps and two sheathed olfactory organs called rhinophores. The body is wedge shaped, being wide at the front and ending in a slender foot with a lateral keel on either side. Half way along the body are two long, thin, postbranchial processes with white tips. These are club-shaped and glandular and have a defensive function. A group of bipinnate or tripinnate gills lies just above and to the front of these processes. The general colour of the body is translucent white and the upper side is covered with orange splotches and small black spots. There is a significant difference in colouring between Atlantic populations and Pacific specimens. The adult length is usually between 15 millimetres (0.6in) and 30 millimetres (1.2 in).[2][3]
Thecacera pennigera has a cosmopolitan distribution, being found in temperate waters on either side of the North Atlantic Ocean, in the Mediterranean Sea, around South and West Africa, Brazil, Japan, Korea, Pakistan and more recently in Australia and New Zealand. When conditions are suitable, it may occur in considerable numbers but often it is sporadic or even rare. It is found at depths of down to 36 metres (120ft) living on arborescent bryozoans. These sometimes foul the hulls of vessels and both have been extending their range, presumably travelling by ship.[2][3]
Like other sea slugs, Thecacera pennigera is a hermaphrodite. Packets of sperm are exchanged by mating pairs of slugs and fertilisation is internal. The fertilised eggs are deposited in strings draped across the substrate, usually bryozoans of the genus Bugula on which the sea slug feeds. It is not clear whether there is a planktonic larval stage or whether juvenile sea slugs hatch direct from the eggs.[2]