Dotted Sea-slug (Peltodoris atromaculata)

Photo credit: Patricia Martin Cabrera

Review: Abdel Rahman El Gamal (Founder of the website)



The photo was taken in Granada (Spain)

Introduction: The species is a marine gastropod molluscs that belongs to the family Discodorididae, class Gastropoda and phylum Mollusca which has been known as Peltodoris atromaculata or sometimes reported as Discodoris atromaculata.

The Dotted Sea-Slug occurs in Mediterranean Sea and has been also observed on the Basque Coast & the Canary Islands in the nearby Atlantic Ocean and is especially found in dark and shady underwater areas at various depths. In particular, the species is usually found on the stony sponge on which it feeds exclusively.

Description: The Dotted Sea-Slug has an oval body and is easily recognized by its randomly distributed dark brown spots on a white background.  It is believed that these spots are clearly visible, probably have the function to signal to potential predators that the animal is not edible (aposematic coloration). When the animal is resting, the outline of his body is nearly circular and hard to the touch.  The average size is from 5 to 7 cm that can grow to approximately 12 cm in length.

Their simple and tiny eyes are able to discern little more than light and dark. The species has feather-like gills on the rear part of the body.  It has eight appendages on three branches and is used by the animal to breathe.  It also has also head-mounted sensory appendages enabling animals to smell and taste.

Feeding habits: The species feeds mainly on the sponge (Petrosia ficiformis) and accumulates natural chemical products, such as petroformynes, from the sponge and stores them in its bodies, rendering themselves distasteful to predators. Most species in the Discodorididae family are thought to feed at night on sponges, while during the day they search for dark areas or remain hidden under rocks.

Reproduction: Dotted sea-slugs are simultaneous hermaphroditic, which means that they have both male and female sex organs at the same time and can fertilize one another. After mating, sea slugs lay their spiral egg masses. Egg development can take between 5 and 50 days, depending on water temperature. Usually from eggs arise little planktonic larvae, called veliger, with shell, which will lose during metamorphosis, when they begin their benthonic life as adult.




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