Sea Hare

Aplysia is a genus of medium-sized to extremely large sea slugs, specifically sea hares, a kind of marine gastropod mollusk. These benthic, herbivorous animals graze in tidal and subtidal zones of tropical waters, mostly in the Indo-Pacific with additional species in the Atlantic and a few in the Mediterranean, and can grow rather large compared with most other mollusks. When threatened they frequently release clouds of ink, believed to help blind an attacker. Following the work of Eric Kandel, the genus, and particularly the species Aplysia californica, has been studied as a model organism by neurobiologists because its gill and siphon withdrawal reflex is mediated by electrical synapses that let several neurons fire in synchrony, and because it has only about 20,000 neurons in total.