Mediterranean Pink Flatworm

Appearance

Prostheceraeus roseus is an oval-shaped flatworm, which reaches a length of 20 mm and a thickness of 1 to 1.5 mm. Its dorsal side has a lilac-pink color, bordered by a white band and a magenta band. The middle line is also a magenta colored band. On both sides of this line are five white lines. At the anterior end of its body are two magenta-colored tentacles.

Naming

Usually there’s a confusion with Prostheceraeus giesbrechtii, because of the missing red colour tones underwater. Human’s eyes are cheated, not beeing able to distinguish between pink and blue. Errors and confusions are also common in scientific literature. There also haven’t been many studies about. WORMS database considers Prostheceraeus roseus a separate species.

Distribution

Prostheceraeus roseus is found on the Mediterranean coast, as well as on that of the Atlantic Ocean, from Portugal to Senegal

Behavior

These and other flatworms can survive in very variable conditions, but if their subsistence is in risk they are able to split in two, regenerating each part a complete animal.

Habitat

Found on hard substrates mainly on slopes at depths of 0 to 60 meters.

Reproduction

Members of the class Turbellaria are mostly hermaphrodites.
Reproduction seems to take place in summer. Each animal has both genders, but usually they reproduce with another specimen. They prick their pin-formed penis through their couple’s skin to exchange their sperm. Eggs are laid isolatedly. Eggs directly hatch into miniature adults.

Food

Flatworms are carnivorous. They wrap their preys up with a slimy secretion which leaves them motionless. Afterwards they push their pharynx out of their mouth, secreting enzymes which predigest their food. Finally they sip their prey.
All of them have predilection for sedentary and colonial animals like bryozoans, cnidarians, sea squirts, molluscs and some crustaceans or tube worms. Prostheceraeus roseus seems to feed on sea squirts of the Pycnoclavella group such as Pycnoclavella nana. They also can detect food at great distances, thanks to smell cells on their head.