Moray eels have a reputation problem. They peer out of holes with their mouths open and their teeth showing, and every instinct a person has says aggressive. Almost none of that reads correctly. The open mouth is breathing, the teeth are for gripping rather than threatening, and the animal is a fairly shy nocturnal predator that would strongly prefer you went away.
They are, however, genuinely remarkable animals, and one thing about how they eat has no parallel in any other vertebrate. Here's what morays actually are, which ones you'll meet on a Punta Cana reef, and how to behave around them.
The Open Mouth Is Breathing
Start here, because it's the single most misread piece of animal behaviour on a Caribbean reef. Most fish pump water over their gills by opening their mouth and flaring rigid gill covers. Morays have small, round gill openings well back on the body and lack that mechanism, so they have to rhythmically gape to drive water through.
That constant open-and-close is respiration. It is not a threat display, it is not the eel sizing you up, and it does not mean you have annoyed it. An eel that is genuinely agitated behaves differently — it withdraws, or it emerges further and moves toward you, which is unmistakable when it happens and is rare.
The Second Jaws
This is the part that makes morays scientifically interesting rather than just atmospheric. Most predatory fish feed by suction — they expand their mouth cavity rapidly and the resulting pressure drop pulls prey in. That works in open water. It does not work when your head is wedged in a hole in a reef, because there's nowhere for the water to go.
Morays evolved a different solution. They have a second set of jaws, called pharyngeal jaws, sitting back in the throat. When the front jaws seize prey, the pharyngeal jaws launch forward into the mouth, grip the prey, and haul it backwards down the throat. Research published in 2007 documented this mechanism in detail, and it appears to be unique among vertebrates — no other backboned animal is known to feed this way.
It's the reason a moray can be a serious predator from inside a crevice, and it's worth knowing simply because the animal in front of you is doing something no shark, no barracuda and no grouper can do.
How They Actually Live
Morays hunt mainly at night, which is why daytime dives usually show you a head in a hole rather than a moving animal. Their eyesight is poor; they hunt almost entirely by smell, and a moray tracking scent through a reef at night is a genuinely effective predator of fish, octopus and crustaceans.
They have no scales. Instead the skin is covered in a thick mucus layer, which in some species is toxic and which lets the animal move through rough coral without injury. It also means a moray is far more delicate to the touch than its appearance suggests — handling one damages that protective layer.
One behaviour worth watching for: cooperative hunting. Groupers have been documented signalling to morays with a head-shake, effectively recruiting them to flush prey out of crevices that the grouper can't enter, so the two hunt the same reef section from opposite sides. It's one of the few well-documented cases of interspecies cooperative hunting among fish, and while it's best described from the Red Sea, grouper-moray associations turn up elsewhere too.
The Ones You'll See in Punta Cana
Spotted moray (Gymnothorax moringa) is the one you'll encounter most often — white or cream with dense dark spotting, usually around a metre, tucked into reef crevices with just the head out. If you see a moray on a Caribbean reef, this is the likeliest identification.
Green moray (Gymnothorax funebris) is the big one, reaching two metres and occasionally more, and it's the species that makes people's eyes widen. There's a good detail here: the eel isn't actually green. Its skin is brown, and the yellowish tint of its protective mucus over brown skin reads as green. Finding one out in the open is one of the better things that can happen on a dive.
Also here: the goldentail moray (Gymnothorax miliaris), small and dark with dense yellow speckling and a yellow tail tip, and one of the more approachable species; the chain moray (Echidna catenata), boldly patterned in dark and yellow chain-link markings, notable for blunt crushing teeth rather than needle ones because it specialises in crabs, and unusual among morays for hunting in daylight and even brief excursions out of water in shallow pools; and the purplemouth moray (Gymnothorax vicinus), mottled and identifiable by the dark purple interior of the mouth.
Bites, and Whose Fault They Are
Moray bites on divers are uncommon, and the circumstances are boringly consistent. Reaching into a hole without looking. Hand-feeding. Cornering an animal that has nowhere to retreat. Grabbing or attempting to handle one. Spearfishing, where the eel is competing for the same fish. Very nearly every documented bite traces back to one of those.
Hand-feeding deserves its own mention because it's the specific behaviour that creates problems for everyone afterwards. An eel conditioned to associate divers with food will approach divers, and a poor-sighted animal lunging at what it thinks is fish can easily take a finger instead. Operators who feed morays are creating a hazard for the next group.
The teeth angle backwards, which is excellent for holding prey and bad for releasing a hand — pulling away tears rather than frees. Bites also carry meaningful infection risk from oral bacteria. A moray bite should be treated by a doctor rather than cleaned and ignored.
The practical version is easy and is just good diving: keep your hands to yourself, never reach into a crevice you can't see into, don't feed anything, don't block an animal's exit, and give it room. Morays are entirely safe to be near and photograph if you leave them alone, which is most of what good reef behaviour amounts to anyway.
Photographing Them
Morays are one of the better macro subjects on a Caribbean reef — they hold still, they're patterned, and the face has genuine character. Approach slowly and from the side rather than straight on. Don't push a lens or strobe into the hole; besides being intrusive, it's exactly the posture that causes bites.
If the eel withdraws, you've come too close. Back off and wait; they frequently re-emerge within a minute or two if you stop advancing. Patience produces far better images here than persistence does.
The Bottom Line
The open mouth is breathing, not aggression — morays lack the gill covers other fish use and must gape to move water. They have pharyngeal jaws in the throat that launch forward to drag prey down, a mechanism documented in 2007 and apparently unique among vertebrates. They hunt at night by smell, have no scales, and are protected by toxic mucus. In Punta Cana you'll most often see spotted morays, sometimes the two-metre green moray — which is brown, the green being mucus over brown skin — plus goldentail, chain and purplemouth. Bites are rare and almost always caused by reaching into holes, hand-feeding or grabbing. Leave them alone and they're excellent company. To go looking for them on a dive, message us through our contact form with your dates.
