Johnston's Balloon Eolis

Tergipes tergipes

Johnston's balloon eolis is a small sea slug, typically measuring between 5 to 8 mm in length. It belongs to the family Tergipedidae and is characterized by its resemblance to Eubranchus exiguus, which often shares the same habitat. This species is primarily found in the NE Atlantic, with its distribution extending from Iceland and Norway down to Portugal, as well as in the Mediterranean Sea. It is important to note that reports of this species from Brazil should be treated with caution, as they may not be accurate. The habitat of Johnston's balloon eolis ranges from depths of 4 to 10 meters, where it inhabits benthic environments. It primarily feeds on hydroids, particularly those of the genus Obelia, which are its preferred food source. The species is known to be hermaphroditic, meaning that individuals possess both male and female reproductive organs. During mating, individuals engage in a behavior where they attempt to induce one another to act as a male or female, with the dominant individual penetrating the body wall of the other. Divers may encounter Johnston's balloon eolis at various dive sites, often on kelp blades where it blends in with its surroundings. Observing this nudibranch can be an intriguing experience, as it showcases the unique adaptations of marine gastropods. Conservation status for this species has not been evaluated, leaving its long-term viability uncertain.