It is a species of sea slug that grows to around 35 mm.
They float partially by means of an air bubble, which they swallow and store in their gastric cavity. They also have a rather unique defence mechanism – they store the nematocysts produced by jellyfish (their prey) in their own tissues to protect against predators. They are found in the waters off of the Big Island, Maui, Oahu and Kauai. They are rarely found on shore unless during periods of on-shore winds which bring them (and their prey) into coastal waters. Neat huh?
