Aplysia is a genus of medium-sized to extremely large sea slugs, specifically sea hares, which are one clade of large sea slugs, marine gastropod mollusks. The general description of sea hares can be found in the article on the superfamily Aplysioidea. These benthic herbivorous creatures can become rather large compared with most other mollusks. They graze in tidal and subtidal zones of tropical waters, mostly in the Indo-Pacific Ocean (23 species); but they can also be found in the Atlantic Ocean (12 species), with a few species occurring in the Mediterranean.