National Geographic: Rare "Prehistoric" Shark Photographed Alive

This serpentine specimen may look like a large eel, but its six slitlike gills help mark it as a cousin of the great white, the hammerhead, and other sharks. But this isn't your average fish.

Believed to have changed little since prehistoric times, the frilled shark is linked to long-extinct species by its slinky shape and by an upper jaw that is part of its skull. Most living sharks have hinged top jaws.