Aplysiidae - Sea Hares
Aplysiidae, the sea hares, are a family of large sea slugs (marine gastropod mollusks) lacking outer shells. Most have an internal shell that is small and very flimsy. It lies within the sea hare's mantle, which is a flap on the back that covers the gills and other internal organisms. Sea hares have wing-like extensions called parapodia on their sides that allows them to swim or glide through the water. These creatures are herbivores and feed on algae and other sea plants. The color of the sea hare's flesh is derived from pigments in the plants they eat. Some species squirt purple or red ink when disturbed or attacked to confuse predators. Sea hares do not produce the ink. It is extracted from the algae in their diet.
Sea hares are hermaphroditic and have both male and female reproductive organs in their body. When they mate, they can be either male or female. They commonly form lines or chains when mating where the 1st animal acts as a female, the last acts as a male, and the animals inbetween act as both male and female.
Because of their relatively simple, large and easily accessible nervous system, sea hares are used extensively for neurobiological studies, especially in the areas of learning and memory.