The Sea Hares of the Aplysiidae Family are large marine opisthobranch gastropod of the Phylum Mollusca. In Mexico they are known as vaquita del mar. The derive their name from their rounded body outline and long projecting rhinophores attached to the head, which give them the shape of a sitting rabbit. They lack the external shell of most gastropods and instead have a small, flimsy, shell buried within the mantle. The mantle also covers the gills and other organs. They have one large exhalant siphon in the middle of the back and a smaller inhalant siphon in front of the shield. The rhinophores are chemosensory organs that detect “scent” in the water and water motion. Sea hares have wing-like flaps (parapodia) along their sides. These parapodia allow the animal a limited amount of swimming ability. Sea hares are perhaps the largest of all gastropods, reaching 99 cm (39 inches) and 14 kg (30 lbs).
Sea Hares are herbivores that consume brown, green and red algae, as well as sea grasses. Some species extract the pigment from the algae and use it as an ink that they secrete as a defense mechanism to avoid predators. Sea Hares are preyed on by fish, flatworms, lobsters, sea slugs, sea spiders, sea turtles, and starfish. Sea Hares are hermaphrodites, possessing both male and female reproductive organs. When mating, they usually form chains of several individuals, alternately functioning as male or females. Sea Hares have a large, relatively simple, and easily accessed nervous system that have made them good subjects for neurobiology studies.
Sea Hares are found worldwide in temperate and tropical waters. Most are found in bays and in shallow coastal waters, at depths less than 40 m (131 feet). There are 70 species in the Aplysiidae Family of which 10 species are found along the West Coast of Mexico.