Purple Flabellina

Overview

Coryphellina rubrolineata is an aeolid nudibranch, a type of sea slug recognized by its slender, tapering body and numerous dorsal projections known as cerata. While historically considered a widespread species, recent research indicates that true populations are primarily restricted to the Red Sea and Arabian Sea, with established populations in the Mediterranean Sea as a result of Lessepsian migration.

Appearance

This species typically features a translucent, milky-white to pale pink body. Its most diagnostic markings are three longitudinal lines—one running down the dorsal midline and one along each side—which range in color from reddish to purple and may appear as continuous stripes or broken, dotted segments. The rhinophores are distinctively pointed and feather-like, often displaying a purple ring near the tip. The cerata are arranged in several groups and frequently exhibit a purple subapical ring with orange or lighter-colored tips. Coloration can be highly variable, with some individuals appearing almost entirely purple or mauve.

Biology & behavior

Like other aeolid nudibranchs, this species possesses a specialized defense mechanism: it can store stinging cells (nematocysts) from the cnidarians it consumes, repurposing them for its own protection. It is commonly found in rocky or coral reef environments where it actively hunts for its primary food source, hydroids. The species is part of a complex of closely related nudibranchs, and its external appearance can be difficult to distinguish from similar species without detailed examination.