Ver Plat Bleu De Méditerranée

Overview

Prostheceraeus giesbrechtii is a striking marine flatworm often referred to as the Mediterranean blue flatworm. Despite its vibrant appearance, which can lead observers to mistake it for a sea slug, it is a member of the order Polycladida.

Distribution & habitat

This species is primarily found in the Mediterranean Sea and parts of the temperate eastern Atlantic Ocean. It typically inhabits rocky substrates, often frequenting areas covered in calcareous algae, cavities, or the undersides of rocks, and is also associated with various sessile organisms.

Appearance

The body of this flatworm is thin, foliaceous, and oval-shaped, with pleated edges and a pointed posterior. Its dorsal surface is characterized by a distinct color pattern featuring blue tones—ranging from light blue to nearly black—interspersed with white longitudinal bands. A hallmark feature is the bright saffron-yellow line running down the center of the back, extending from the cerebral eyespots to the rear of the animal. The entire perimeter of the body is typically margined in white, and the anterior end features two small, dark-colored tentacles.

Biology & behavior

Like other polyclad flatworms, this species is a simultaneous hermaphrodite. It is a predatory carnivore, known to feed on sessile organisms such as sea squirts. While it is a showy and recognizable inhabitant of the reef, it is generally considered unsuitable for aquarium environments.