Warty Sidegill Slug

Pleurobranchus areolatus

Pleurobranchus areolatus is an oval-shaped sea slug that can grow up to 15 cm in length. Its body features numerous small, flat, polygonal tubercles, with a color range that varies from light brown to deep violet, often marked with opaque white pigments. This species is typically found in the Caribbean Sea, inhabiting areas under rocks and coral rubble, and can be encountered at depths ranging from 0 to 70 meters, although most records indicate it is usually found shallower than 40 meters. It has been recorded at multiple dive sites across regions including Mexico, Costa Rica, and the Bahamas, with its type locality being Saint Thomas in the U.S. Virgin Islands. Feeding primarily on ascidians, such as Didemnum sp., Pleurobranchus areolatus is a carnivorous species. During spring, it lays large, translucent, gelatinous egg masses. The reproductive system is triaulic, featuring two female openings and one male opening. Encounters with this species during dives can be intriguing, as divers may observe its unique coloration and body structure while it rests on the seafloor or among corals. The species has been noted for its chemical defenses, with compounds isolated from it that may originate from its diet or symbiotic relationships. While the conservation status of Pleurobranchus areolatus has not been evaluated by the IUCN, it is considered to be abundant in certain regions, such as Biscayne Bay, Florida.