Moray eel (Thomas Quine / CC BY)
Moray eels (Muraenidae) have slender, prolonged, scaleless bodies and large mouths with numerous fang-like teeth. They range from 11.5 centimeters (4.5 inches, Anarchias leucurus) to 4 meters (13 feet, slender giant moray) in length. Moray eels are not aggressive to divers. However, some species will bite if provoked.