Berthella

Berthella is a genus of sea slugs, specifically side-gill slugs, belonging to the family Pleurobranchidae. These marine gastropod molluscs are characterized by a prominent gill located on the right side of their body, between the mantle and the foot.

Berthella species are found in various marine environments worldwide, often in temperate and tropical waters. They are generally small in size, typically less than a few centimeters in length. Their bodies are typically smooth and gelatinous, with a simple, often oval, shape. Coloration varies amongst different species and can range from translucent white or yellow to brown or even mottled patterns.

These sea slugs are typically nocturnal and feed on sponges, tunicates, or other encrusting organisms. They are hermaphroditic, possessing both male and female reproductive organs. Reproduction involves the laying of egg masses, which are often attached to the substrate.

The taxonomy of Berthella has undergone revisions, and the classification of some species within the genus is still subject to ongoing research and debate. Some species formerly classified under Berthella may have been reclassified into other genera within the Pleurobranchidae family.