Trapania maculata is a nudibranch belonging to the Goniodorididae family. It is a species that mainly inhabits rocky walls where it does not get direct light, but rather those darker areas. Its geographical distribution includes both the waters of the eastern Atlantic Ocean and the Mediterranean Sea, where we can find specimens up to 20 meters deep.
Trapania maculata specimens can grow to a maximum total length of almost 2 cm. The body is elongated and relatively tall, with a translucent milky white color. In the cephalic area we find a pair of triangular-shaped buccal palps in the lower part, as well as a second pair of palps, these oriented backwards and larger than the buccal ones. After this second pair of palps, we find two rhinophores with a smooth base and the upper third with lamellar structures. We will find a series of orange or yellowish, irregularly shaped spots on the dorsal part of the head, oral and buccal palps, rhinophores, dorsum, flanks of the body, gill blades and tail. Finally, the tail is relatively pointed and its length represents approximately one third of the total length.
Specimens of Trapania maculata are frequently sighted on various sponges of the genera Ircina, Sarcostragus and Chondriosia. Although for a long time it was believed that Trapania maculata fed on these sponges, more recent studies have shown that they actually feed on symbiont hydrozoans that grow on the surface of these sponges, with the hydrozoan Eudendrium ramosum being the basis of their feed.
As for the reproduction of Trapania maculata, this occurs during the spring and summer months. It is a hermaphrodite species that requires cross-fertilization between two specimens. The eggs are laid in a gelatinous, translucent, flat cord-shaped structure, 3 to 4 mm high, which is irregularly rolled up. Inside we find the small white eggs that are irregularly arranged on the inside of the ribbon.
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