From Wikipedia: "Moray eels' heads are too narrow to create the negative pressure that most fish use to swallow prey. Quite possibly because of this, they have a SECOND SET OF JAWS called pharyngeal jaws, which also possess teeth. When feeding, morays launch these jaws into the mouth, where they grasp prey and transport it into the throat and digestive system. Moray eels are the only animal that uses pharyngeal jaws to actively capture and restrain prey. Larger morays are capable of seriously wounding humans." Read More...(external link). See my YouTube Video of Green Morays.