A moray has a long, snake-like body with no scales. Morays belong to the eel order Anguilliformes. As of November 2026, scientists count about 200 species of moray eel, and the order has more than 800 eel species worldwide. A 2012 checklist of the world's moray eels recognizes 15 genera and two subfamilies.

Moray eels live in tropical seas, on coral reefs and rocky reefs, and the green moray lives in the western Atlantic Ocean, from New Jersey and Bermuda to the Gulf of Mexico and Brazil. The California moray lives along the Pacific coast, from Point Conception, California, south to Magdalena Bay, Baja California.

As of November 2026, these sizes are reported. The giant moray is reported to reach about 3 meters long and can weigh up to 30 kilograms, and the green moray can reach 2.5 meters and weigh up to 29 kilograms. The California moray can grow to about 5 feet, or 1.5 meters, and morays range in length from about 20 centimeters, the redface eel, to 3.75 meters, the longtail moray.

A moray keeps opening and closing its mouth, which moves water over its gills so it can breathe. A green moray's gills and gill slits are very small, because this fairly still fish does not need as much oxygen as more active fishes, and a moray's gill opening is a small pore on the side of its head.

Fish swim like eels by bending the whole body into waves from side to side, which is called anguilliform swimming. A moray can swim backward almost as well as forward, and this helps it back into a crevice, and because morays lack paired fins, they are not very stable, and it is not unusual to see one lying on its side or upside down.

Smell is a moray's strongest sense, and it uses smell to find food. It has tube-shaped nostrils on its snout that it uses to smell, and the giant moray has very poor eyesight. A moray's lateral line pores are found only on the front part of the body.

Morays lay eggs, and the eggs are fertilized outside the body, and one published source recorded ripe green moray eggs measuring 1 millimeter across from a 1.1-meter female, while other sources suggest the eggs of other morays are 3 to 4 millimeters. A baby moray is a see-through, leaf-shaped larva called a leptocephalus, and a green moray's larva grows to between 5 and 10 centimeters long. Moray larvae have pectoral fins, which the adults lack, and 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. Juvenile California morays can be found in tidal pools, and adults move to deeper water, and some moray species are thought to live about 30 years or more.

Most bony fish are suction feeders; even the mudskipper, which takes prey on land, carries water in its mouth to use suction. A moray cannot pull in prey with strong suction, and many fish have extra jaws in their throats that filter food from water or grind prey when swallowing. The first throat jaws known to be adapted to help catch prey, not just swallow it, are the extendable jaws of morays, according to the researchers in the 2007 Nature study.

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 to see the throat jaws work, UC Davis researchers took X-rays of eels eating dead goldfish. High-speed video and X-rays showed that the throat jaws lunge forward into the mouth and pull prey into the throat, and a moray has a second set of jaws in its throat. The moray's two sets of jaws work like a double bite, which the Nature study compared to the way snakes swallow large prey in stages.

Researchers measured the bite force of 49 live California morays, each 567 to 1,192 millimeters long, and the bites ranged from about 32 to 467 newtons, and in California morays, bite force grew faster than head size, so larger morays bite harder for their head and body size. A zebra moray's strongest measured bite was 159.2 newtons, while two models had estimated 57.1 and 59.3 newtons.

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. 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, and morays with blunt crushing teeth feed mostly on crustaceans.

Morays that eat fish have sharper teeth and longer skulls. Moray teeth point backward. Mehta found that hard-shell-eating morays had skulls that support thicker cheek muscles, the better to bite harder. They also had thicker stomach walls, perhaps to protect them from shards of shell, and hard-shell-eating morays had smaller hearts than other morays, possibly because they do not have to swim as much to catch prey.

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, and over the years Mehta's team returned to their field sites, they repeatedly trapped many eels in the same location, a tendency called site fidelity. At Catalina Island's Blue Cavern marine protected area, Mehta's team trapped and measured 1,736 eels over three years and found more, larger and older eels inside the protected area than outside it.

In December 2006, Redouan Bshary of the University of Neuchatel and colleagues described groupers and giant morays hunting together in the Red Sea, in the journal PLoS Biology. 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. The moray can enter reef crevices, while the grouper hunts in open water around the reef.

In the study, groupers hunt by day in open water and giant morays are evasive nocturnal hunters, and both animals hunted more successfully when together than when hunting alone. Groupers signal to morays more often when the groupers are hungry, although the researchers never saw a moray signal to a grouper, and they concluded that giant morays broaden their hunting activity to daylight hours because of their interactions with groupers. They called the joint hunting a by-product mutualism: each animal uses only its own hunting strategy and both gain from the joint movements.

Words to know

• durophagy: shell-eating
• suction: pulling force
• mutualism: helping each other
• anguilliform: eel-like swimming
• larva: young form