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24, Apr, 2013

Giant Moray Eels – Gymnothorax javanicus

Posted in Fish Finder, Individual Subject Tricks, Latest News, Liquid Lense, Marine Life, Tips & Tricks, Underwater Photography Tips by tasha

Giant Moray Eels (Gymnothorax javanicus,) are from the family Muraenidae.
Giant Moray Eels are cosmopolitan creatures, found in both tropical and temperate seas, although the largest populations can be found in the coral reefs of warm oceans. They are widespread in the Indo-Pacific region; being found in the Andaman Sea, the Red Sea, East Africa, the Pitcairn Islands, Ryukyu and Hawaiian islands, New Caledonia, Fiji and the Austral Islands. They are usually found in shallow water among the reefs and rocks and in lagoons.


Interesting Facts about Giant Moray Eels

Juvenile Giant Moray Eels are tan in colour, with large black spots. Adults have black specks, which graduate, into leopard skin type spots behind the head, with a black area surrounding the gill opening.

Giant Moray Eels - Gymnothorax javanicus -White Balance Shot

In terms of body mass, Giant Moray Eels are the largest of the moray eel species (Muraenidae,) reaching up to 3 metres (9.8 ft) in length and 30 kg (66 lb) in weight. Their body is long and heavily set, but despite this, they are very flexible and move with ease through the water. Their dorsal fin extends from just behind their head, along their back and joins seamlessly with their caudal and anal fins. Giant Moray Eels do not have pectoral or pelvic fins, this gives them their serpentine snake like appearance. They have poor eyesight, due to their small eyes, and so Giant Moray Eels rely on their highly developed sense of smell, as they lie in wait to ambush their prey.

Giant Moray Eels are carnivorous creatures and feed primarily on other fish cephalopods, molluscs and crustaceans. They will also eat other species of eel and have been known to engage in cooperative hunting with the Roving Coral Grouper (Plectropomus pessuliferus.) The invitation to hunt is initiated by head shaking. The reason for them joining forces is that the Giant Moray Eel has the ability to enter narrow crevices and flush out prey that are not accessible to groupers. This is the only known instance of different species joining forces in the hunt for fish.

Giant Moray Eels rest in crevices during the day and hunt nocturnally, although they may ensnare small fish and crustaceans that pass by during the day. Their jaws are wide, framing a protruding snout.
The Giant Moray Eel has a unique way of swallowing it’s prey. This is due to their alien like second set of jaws (pharyngeal jaws,) which they have at the back of their throat. When they lash out at their prey, they grab them with their first set of jaws, then with the second, while still holding it with the first set. When the second set of jaws has a hold on the prey, it pulls the prey into the digestive system. Giant Moray Eels are the only animal in the world that uses its pharyngeal jaws whilst hunting, to capture and restrain their prey.

Giant Moray Eels - Gymnothorax javanicus - being cleaned

Giant Moray Eels travel up to 4,000 miles to breed, a journey which can take up to seven months. During that time, it is believed that the eels do not eat. Instead, they use their body fat and muscle tissue for nutrients. Courtship among compatible morays begins when water temperatures reach their highest, and they begin sexual posturing in the form of gaping widely. Then the morays will wrap each others’ long slender bodies together, either as a couple or 2 males and a female. They simultaneously release sperm and eggs as act of fertilisation, which signals the end of their relationship. Sadly, they will die after the process of breeding.

On hatching, the eggs take the form of leptocephalus larvae, which look like thin leaf-shaped objects, which float in the open ocean on ocean currents, for about 8 months. They swim down to begin life on the reef and eventually, after 3 years, become a moray eel, living for anything from 6 to 36 years.

Scientific studies have shown hermaproditism in morays, some being sequential (they are male, later becoming female) and others are synchronous (having both functional testes and ovaries at the same time) and can reproduce with either sex, depending on species in a natural life cycle.

Giant Moray Eels - Gymnothorax javanicus - close up shot

Giant Morays Eels are frequently thought of as particularly vicious or ill-tempered creatures. In truth, Giant Moray Eels hide from humans in crevices and would rather flee than fight. They are shy and secretive and attack humans only in self-defense, or mistaken identity. Most attacks occur when divers hand feed Giant Moray Eels, an activity often used by dive companies to attract tourists. Giant Moray Eels have poor vision and rely mostly on their acute sense of smell, this makes it difficult for them to distinguish between fingers and food held out for them. Numerous divers have lost fingers while attempting feed Giant Moray Eels, and so hand feeding of moray eels has been banned in some locations, including the Great Barrier Reef. The moray’s rear-hooked teeth and primitive but strong bite mechanism also makes bites on humans more severe, as the eel cannot release its grip, even in death, and must be manually prised off.
Please don’t hand feed Giant Moray Eels.

Giant Moray Eels are fished, but are not considered endangered. This is due to the fact that they are very dangerous for humans to eat. They contain high levels of a toxin called Ciguatoxin. This fact was apparently the cause of the death of King Henry I of England, who died shortly after feasting on a Moray Eel.

At Scubafish we encounter Giant Moray Eels at all of our dive destinations, but the larger Giant Moray Eels are more commonly seen at the dive sites of Hin Daeng & Hin Muang.


Giant Moray Eels - Gymnothorax javanicus - shot with strobe


Techniques and ideas when Photographing Giant Moray Eels

  • Don’t crowd a Giant Moray Eel, approach slowly and don’t scare or startle them
  • Never surround them, don’t chase after them and don’t ever touch them
  • A close-up portrait shot works really well, make sure their eyes are in focus
  • Try to photograph them with their mouth open
  • Be careful when positioning yourself, make sure not to disturb the seabed, as this can frighten other sea creatures and also cause a cloud of backscatter, making it impossible to take your photograph


All images are taken at the dive sites around Ko Lanta, by professional Liquid Lense Underwater Digital Imaging Specialist, Natasha Lambelin.

Giant Moray - Gymnothorax javanicus -Portrait Shot



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