Flatworm – Pseudoceros maximus

Flatworm Pseudoceros maximus flatworms species Plathelminthes Mediterranean Sea scuba diving canary islands
Flatworm – Pseudoceros maximus
This specimen was found in a tide pool in Valle ran Rey, La Gomera.

The Flatworm is a species in the phylum of Platyhelminthes. Pseudoceros maximus was first described by Lang in 1884.

Description, Anatomy & Characteristics

The Flatworm has a flat, elongated oval body. Its colour can vary. Either it is brown with lighter speckled spots or vice versa. Sometimes parts are also painted black. A rise along the longitudinal axis of the animal is conspicuous. However, this does not reach to the front and rear end of the body. Two tentacle-like folds are also found at the head end.

Pseudoceros maximus grows up to 4cm long.

Habitat & Distribution

The Flatworm lives on rocky ground with growth of sponges or plants. I found it at a depth of 10cm in a tidal pool on La Gomera.

When scuba diving on the Canary Islands, the species can only be observed very rarely. That’s probably mainly because of the size and the good camouflage.

The distribution area of Pseudoceros maximus extends over the entire Mediterranean Sea and the adjacent Atlantic Ocean.

Biology, Feeding & Reproduction

It is carnivorous and therefore a predator. Their diet consists of sponges, moss animals, tunicates and small crustaceans. The Flatworm usually recognizes its food by its chemoreceptors at a certain distance. Thanks to its well branched digestive system, nutrients can reach all parts of the body. Anything that cannot be digested is excreted through the mouth due to the lack of an anus.

Like many other flatworms, Pseudoceros maximus is a hermaphrodite. That is, every animal has both sexes, the male and the female. With the reproduction, the animals fertilize themselves mutually. After mating, the egg or fertilised eggs form a small cocoon together with some nutrient cells. These are fixed under stones or plants. When the cocoons hatch, the embryos turn into a larva. It lives planktonic for a short time until it sinks to the seabed.

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