Are sea slugs related to land slugs?
Both land and sea slugs are molluscs in the class Gastropoda, which means ‘stomach foot’, so are closely related and found all over the world. On land, slugs have no shell, but it’s not that straightforward in the sea. Some species called nudibranchs start off with a shell, but lose them as an adult and have external gills. There are even some that look like slugs, but aren’t slugs at all. Sea hares have an internal shell, so are actually a sea snail, and sea cucumbers are in a totally different family altogether.