This gallery consists of nudibranchs, flat worms, and related families. These animals are noted for their often extraordinary colors and striking forms. There are more than 3,000 described species of nudibranchs, which are casually referred to as "sea slugs," but that term includes many other animals that belong to other taxonomic groups.
Nudibranchs generally "breathe" through a branchial plume of bushy extremities on their back, rather than using gills. Nudibranchs are hermaphroditic, having a male and female set of reproductive organs.
Flatworms are also very colorful, but thin and delicate. These creatures can quickly glide along the bottom of the ocean, or, when disturbed, they can swim for a considerable period of time by throwing the sides of their body into undulating waves. It is estimated that there are over 100,000 species of flatworms in the world, and there are many species that remain unidentified. For more information, see www.seaslugforum.com