A moray eel has a long, snake-like body and no scales, and moray eels live in tropical seas, on coral reefs and rocky reefs. Morays belong to the eel order Anguilliformes, which has more than 800 eel species worldwide as of November 2026, and as of November 2026, scientists count about 200 species of moray eel. As of November 2026, the giant moray is reported to reach about 3 meters long and can weigh up to 30 kilograms, while the green moray can reach 2.5 meters and weigh up to 29 kilograms. The green moray's size and weight are the largest reported for that species. Scientists have studied morays with high-speed video, X-rays, traps and museum collections.

Fish swim like eels by bending the whole body into waves from side to side, and this is called anguilliform swimming. Morays have no paired fins, which means they have no pectoral fins and no pelvic fins, so they are not very stable, and it is not unusual to see one lying on its side or upside down. Scientists comparing 54 eel groups found that morays have more vertebrae in the tail region of the spine than the other two major groups of eels. A fish's spine can be made longer by adding vertebrae at the front, adding them at the tail end, or making each vertebra longer. Vertebrae are the bones that make up the backbone.

A moray often hides in a crack in the rocks with only its head showing, and it can swim backward almost as well as forward, which helps it back into a crevice. Most moray eels hunt at night. Smell is a moray's strongest sense, and it uses smell to find food. A moray has tube-shaped nostrils on its snout that it uses to smell. The giant moray has very poor eyesight and relies on its sense of smell to find food. A crevice is a narrow crack, and a nostril is an opening in the nose.

Many moray eels have sharp teeth, and moray teeth point backward. Moray teeth differ from one kind of moray to another, because some morays have sharp, fang-like teeth and others have low, blunt teeth for crushing, and morays with blunt crushing teeth feed mostly on crustaceans. Morays eat fish, octopuses and crustaceans, and the California moray eats small reef fish, octopuses, shrimps and crabs. Studies of moray diets found they eat small fish, octopus, shrimp, and hard-shelled prey such as mollusks and crabs. Zebra morays are thought to be the hallmark of durophagy, which means their diet is mainly hard-shelled prey such as crabs and reef urchins. Durophagy is a word for eating hard-shelled food.

A moray cannot pull in prey with strong suction, unlike many fish. Many fish have extra jaws in their throats that filter food from water or grind prey when swallowing, and a moray has a second set of jaws in its throat too. High-speed video and X-rays showed that a moray's throat jaws lunge forward into its mouth and pull prey into the throat. Rita Mehta was the first to video the moray's double jaws in action, as a postdoctoral researcher in Peter Wainwright's lab at UC Davis, and the researchers in the 2007 Nature study found that these are the first throat jaws known to be adapted to help catch prey, not just swallow it. A moray can also tie its body into a knot to get leverage when it eats, and some moray eels can take prey on land without using water, which no other fish is known to do.

Before Mehta began studying California morays in 2010, no one thought many morays lived in the area. Mehta and Higgins trapped, examined and tagged 462 California morays at Two Harbors in just a few weeks. Over the years Mehta's team returned to their California moray field sites, they repeatedly trapped many eels in the same location, a tendency called site fidelity. To learn what morays eat, Mehta searched databases for reports on moray prey and catalogued stomach contents of museum specimens. California morays at Catalina Island specialize on kelp bass as prey.

In the Red Sea, groupers and giant morays have been seen hunting together. Redouan Bshary of the University of Neuchatel and colleagues described this in the journal PLoS Biology in December 2006. A grouper approaches a resting giant moray and shakes its head 3 to 6 times a second a few centimeters in front of it, and the moray then leaves its crevice and swims through the reef with the grouper. In the Red Sea study, groupers hunt by day in open water and giant morays are evasive nocturnal hunters. Groupers signal to morays more often when the groupers are hungry, and both groupers and giant morays hunted more successfully when together than when hunting alone.

Morays lay eggs. A baby moray is a see-through, leaf-shaped larva called a leptocephalus, and muraenid leptocephali, which are moray larvae, have pectoral fins that the adults lack. The fins are absorbed when the larva changes into a juvenile. A young moray first drifts in open water as a larva before it settles near the bottom, and spotted moray larvae can take up to a year to grow large enough to swim down to the reef. Once grown, some moray species are thought to live about 30 years or more.

A moray is a long, snake-like eel without scales that often hides in a crack in the rocks and, as most moray eels do, hunts at night. It uses smell to find food, and it eats fish, octopuses and crustaceans. It has a second set of jaws in its throat, and it cannot pull in prey with strong suction. Scientists learned about morays by filming with high-speed video and X-rays, by searching databases and museum specimens, by trapping and tagging eels, and by watching groupers and giant morays hunt together in the Red Sea, where both hunted more successfully than they did alone.

Words to know

• crevice: narrow crack
• suction: pulling force
• larva: young form
• durophagy: shell-eating
• vertebrae: backbone bones