Most bioluminescent Shark
The Cookiecutter shark (Isistius Brasiliensis) from the central regions of the Atlantic and Pacific is the brightest shark. It is named after Isis, an Egyptian goddess associated with light. Up to 5 ft long, it has a dull brown upper surface, but underneath it is often covered entirely with photophores, light-producing organs with emit a very bright, ghostly green glow. The purpose of this bioluminescence is unclear-it may serve to attract sharks of its own species, or to attract prey, or even as camouflage if viewed from below.
Picture of Isistius Brasiliensis