The Blue Dragon

Glaucus Atlanticus (a.k.a. The Blue Dragon) is a sea slug in the solid nudibranch category. The Blue Dragon is pelagic (doesn't live near bottom or shore), and it floats upside down on the surface of the water. The blue dragon is exceptional among sea lugs in its ability to first eat venomous creatures, and then use that venom for their own purposes (often in more concentrated an lethal doses than the original organism would administer). These slugs will eat other pelagic organisms including the Portugese man-of-war, which have a venom that is very painful to humans. The general affects of the venom are shock, fever, heart and lung problems, and has on very rare occasions lead to death.

Blue Dragon:

Blue Dragon upside down: