Sea Slug

Sea Slug:  Sea slug is a common name used for several different groups of saltwater snails that either lack a shell or have only an internal shell, in other words this name is used for various lineages of marine gastropod mollusks that are either not conchiferous (shell-bearing) or appear not to be. The phrase "sea slug" is often applied to nudibranchs, members of the order Nudibranchia within the opisthobranch gastropods. Many nudibranchs are colorful and are a noticeable part of the underwater fauna. However the phrase "sea slug" is also applied to various other groups within the Opisthobranchia including the sea hares, the sacoglossans, various families of bubble snails (Cephalaspidea) and others, some of which have reduced shells, and many of which are shell-less.

Other groups of shell-less or reduced-shell marine gastropods which are sometimes called sea slugs include the sorbeoconch family Pterotracheoidea and the pulmonate (air-breathing) sea slug family Onchidiidae. Reproduction. Sea slugs mating habits are quite unique in that they are hermaphrodites, equipped with both male and female reproductive organs. Although these subtidal mollusk live alone for most of the year, during the mating season in the summer the sea slugs congregate in breeding colonies ironically named brothels[citation needed]. In these mating pools the sea slugs climb all over each other transferring sperm from one to another. This goes on for a few days every year.

 Sea Slug

 Sea Slug

 Sea Slug

Sea Slug