Opistobranch gastropods gallery

Opisthobranchs are marine gastropod molluscs that have the common characteristic of having gills at the back of the heart. Some have a shell which is generally hidden by the mantle (sea hares), others have no shell at all (sea slugs). Molluscs are soft-bodied animals (from the Latin mollis = soft), generally protected by a shell which can be simple, with plates or with two valves. They have gills or lungs and a muscular foot, transformed in cephalopods into tentacles.