Mediterranean Violet Aeolid

Flabellina affinis is a species of sea slug, an aeolid nudibranch, a marine gastropod mollusk in the family Flabellinidae. It is the type species of the genus Flabellina.

Description

The species can grow to a length of 50 mm. Cerata are white-tipped, though for some specimens they're barely visible. Below their white tips is an opaque-ish violet ring. Below that, transparent with orange inside. Sometimes the cerata are clumped together; sometimes they appear separately and in nice rows. It has the pair of long, ridged (annulate) tentacles are rhinophores. The long tentacles below the rhinophores are the oral tentacles; below that, the propodial tentacles.

Flabellina affinis is often confused with Flabellina ischitana, but can be distinguished as follows:

• Flabellina affinis: the outer part of the digestive gland in each ceras is not visible as the area beneath the subapical white ring is opaque violet in colour.
• Flabellina ischitana: the ceratal surface has no purple-violet colouration and is translucent.

Distribution

This species is found in depths to 50 m in European waters in the Atlantic Ocean from Portugal to Ghana and the Canaries and is widespread in the Mediterranean Sea.

Habitat

It feeds primarily on species of Eudendrium, a very common hydroid genus in the Mediterranean Sea.