Mediterranean Violet Aeolid

Overview

The Mediterranean Violet Aeolid (Flabellina affinis) is a striking nudibranch frequently encountered in the Mediterranean Sea and parts of the eastern Atlantic. This small, colorful sea slug is easily recognized by its vibrant violet body and distinctive cerata, making it a favorite subject for underwater macro photography.

Appearance

Growing to a length of 3 to 5 cm, this species features an elongated, tapering body. Its most notable characteristics include long, smooth oral tentacles and ringed rhinophores. The dorsal surface is covered in groups of 3 to 9 cerata, which are reddish-pink and somewhat transparent. A key diagnostic feature is the opaque violet band located just beneath the subapical white tip of each ceras, which obscures the internal digestive gland. This helps distinguish it from similar species like Paraflabellina ischitana, which lacks this opaque purple coloration.

Distribution & habitat

This nudibranch is widespread throughout the Mediterranean Sea and extends along the eastern Atlantic coast from Portugal to Ghana, including the Canary Islands. It is typically found in rocky reef environments, often residing on or near its primary food source at depths ranging from the surface down to 50 meters.

Feeding

Flabellina affinis is a specialized predator that feeds primarily on colonial hydroids of the genus Eudendrium. It is often observed directly on these hydroid colonies, which provide both its food and a suitable substrate for its activities. Like other aeolid nudibranchs, it can sequester undigested stinging cells (cnidocytes) from its prey, storing them in specialized structures called cnidosacs for its own defense.

Reproduction

As a simultaneous hermaphrodite, each individual possesses both male and female reproductive organs. They lay their eggs in characteristic pink or violet ribbons, which are typically deposited directly onto the hydroid colonies they inhabit.