Strikingly beautiful pictures of aquatic, land, and air creatures
This is Nembrotha cristata, a colourful sea-slug found in the tropical Indo-West Pacific Ocean. They grow to about 50mm in length and have black bodies with a strange luminous green "trim". Like most nudibranchs, they deliver a painful string. They do not produce the stinging cells themselves but incorporate them into their own tissues from their prey, stinging jellyfish.