Larval Leaf Scorpionfish (photograph by Chris Newbert, Minden Pictures). Lacking any other defense, many larval fish have adapted transparency as a method of camouflage—such as this tiny, see-through larval leaf scorpionfish in Hawaii.
Glaucus atlanticus (commonly known as the sea swallow, blue angel, blue glaucus, blue dragon, blue sea slug and blue ocean slug). This little sea slug eats poisonous jellyfish and stores their venom for its personal use
This is Nembrotha cristata, a colourful sea-slug found in the tropical Indo-West Pacific Ocean. They grow to about in length and have black bodies with a strange luminous green "trim". They deliver a painful sting.