Peltodoris atromaculata, commonly known as the Dotted Sea-Slug, is a distinctive dorid nudibranch. This fascinating marine gastropod mollusc belongs to the family Discodorididae, superfamily Doridoidea, class Gastropoda, and phylum Mollusca. Known by various names in different languages, it is a notable species in the Mediterranean Sea, frequently spotted around Gozo, Malta’s sister island.
Identifying Peltodoris atromaculata is relatively easy due to its unique appearance. The sea slug features an oval body adorned with random dark brown spots on a white background. These spots are usually larger and darker in the central portion of the body. When at rest, its body appears nearly circular and feels hard to the touch. The average size of this nudibranch ranges from 5 to 7 cm, but it can grow up to 12 cm.
Peltodoris atromaculata is known for its distinctive coloration and defensive features. Its body is dotted with dark brown spots that serve as a warning to predators about its unpalatability—a phenomenon known as aposematic coloration. The nudibranch has feather-like gills on the rear part of its body, consisting of eight appendages on three branches used for breathing. Additionally, it has two rhinophores on the front part of the body, which are olfactory organs with twenty-five lamellae to increase the surface area for detecting molecules in the water. Both the gills and rhinophores are white and retract quickly when the animal feels threatened, slowly re-emerging once the danger has passed.
Peltodoris atromaculata is commonly found in dark, shady underwater areas, such as caves and on the walls or ceilings of underwater structures. It inhabits various depths and is particularly associated with the stony sponge Petrosia ficiformis, on which it feeds exclusively. This habitat preference is crucial for its survival and feeding behavior, making it a specialized feeder within its ecosystem.
An interesting fact about Peltodoris atromaculata is its geographical distribution. While long considered endemic to the Mediterranean Sea, it has also been observed along the Basque Coast and the Canary Islands in the nearby Atlantic Ocean. This broader distribution highlights its adaptability and resilience in various marine environments.
Diving in Gozo offers excellent diving opportunities to observe Peltodoris atromaculata in its natural habitat. Macro diving sites where this nudibranch can be spotted include:
Diving in these locations allows enthusiasts to appreciate the vibrant marine life of Gozo and the unique characteristics of Peltodoris atromaculata, making for an enriching underwater experience.
