Home      Discussion      Topics      Dictionary      Almanac
Signup       Login
Moray eel

Moray eel

Overview
Moray eels are cosmopolitan eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

, but several species are regularly seen in brackish water and a few, for example the freshwater moray (Gymnothorax polyuranodon) can sometimes be found in freshwater. With a maximum length of 11.5 centimetres (4.5 in), the smallest moray is likely the Snyder's moray (Anarchias leucurus), while the longest species, the slender giant moray
Slender giant moray
The slender giant moray or gangetic moray, Strophidon sathete, is the longest member of the family of moray eels. Specimen as large as 4 m have been recorded...

 (Strophidon sathete) reaches up to 4 metres (13.1 ft).
Discussion
Ask a question about 'Moray eel'
Start a new discussion about 'Moray eel'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Recent Discussions
Encyclopedia
Moray eels are cosmopolitan eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

s of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Muraenidae. The approximately 200 species in 15 genera are almost exclusively marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...

, but several species are regularly seen in brackish water and a few, for example the freshwater moray (Gymnothorax polyuranodon) can sometimes be found in freshwater. With a maximum length of 11.5 centimetres (4.5 in), the smallest moray is likely the Snyder's moray (Anarchias leucurus), while the longest species, the slender giant moray
Slender giant moray
The slender giant moray or gangetic moray, Strophidon sathete, is the longest member of the family of moray eels. Specimen as large as 4 m have been recorded...

 (Strophidon sathete) reaches up to 4 metres (13.1 ft). The largest in terms of total mass is the giant moray
Giant moray
The giant moray is the largest of the Moray eels, in terms of body mass .-Range:The giant moray is widespread in the Indo-Pacific region, being found in the Red Sea and East Africa, the Pitcairn group, north to the Ryukyu and Hawaiian islands, south to New Caledonia, Fiji and the Austral...

 (Gymnothorax javanicus), which reaches almost 3 metres (9.8 ft) and can weigh over 36 kilograms (79.4 lb).

Anatomy



The dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...

 extends from just behind the head along the back and joins seamlessly with the caudal and anal fins. Most species lack pectoral and pelvic fins, adding to their serpentine appearance. Their eyes are rather small; morays rely on their highly developed sense of smell, lying in wait to ambush prey.

The body is generally patterned. Camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

 is also present inside the mouth. Their jaws are wide, framing a protruding snout. They possess large teeth, designed to tear flesh as opposed to holding or chewing.


Moray eels' heads are too narrow to create the negative pressure
Suction
Suction is the flow of a fluid into a partial vacuum, or region of low pressure. The pressure gradient between this region and the ambient pressure will propel matter toward the low pressure area. Suction is popularly thought of as an attractive effect, which is incorrect since vacuums do not...

 that most fish use to swallow prey. Quite possibly because of this, they have a second set of jaws in their throat called pharyngeal jaws
Pharyngeal jaws
Pharyngeal jaws are a "second set" of jaws contained within an animal's throat, or pharynx, distinct from the primary jaws. They are believed to have originated as modified gill arches, in much the same way as oral 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.

Morays secrete a protective mucus over their smooth, scaleless skin which in some species contains a toxin. Morays have much thicker skin and high densities of goblet cell
Goblet cell
Goblet cells are glandular simple columnar epithelial cells whose sole function is to secrete mucin, which dissolves in water to form mucus. They use both apocrine and merocrine methods for secretion....

s in the epidermis that allows mucus to be produced at a higher rate than in other eel species. This allows sand granules to adhere to the sides of their burrows in sand-dwelling morays, thus making the walls of the burrow more permanent due to the glycosylation
Glycosylation
Glycosylation is the reaction in which a carbohydrate, i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule . In biology glycosylation refers to the enzymatic process that attaches glycans to proteins, lipids, or other organic molecules...

 of mucins in mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

. Their small circular gill
Gill
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water, afterward excreting carbon dioxide. The gills of some species such as hermit crabs have adapted to allow respiration on land provided they are kept moist...

s, located on the flanks far posterior to the mouth, require the moray to maintain a gap in order to facilitate respiration.

Morays are carnivorous and feed primarily on other fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, cephalopod
Cephalopod
A cephalopod is any member of the molluscan class Cephalopoda . These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, and a set of arms or tentacles modified from the primitive molluscan foot...

s, molluscs, and crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...

s. Grouper
Grouper
Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes.Not all serranids are called groupers; the family also includes the sea basses. The common name grouper is usually given to fish in one of two large genera: Epinephelus...

s, barracuda
Barracuda
The barracuda is a ray-finned fish known for its large size and fearsome appearance. Its body is long, fairly compressed, and covered with small, smooth scales. Some species could reach up to 1.8m in length and 30 cm in width...

s and sea snakes are among their few predators. There is a commercial fishery for several species, but some cause ciguatera fish poisoning. Morays hide in reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

 crevices until their prey is close enough for capture. They then lunge out and clamp the prey in their strong jaw
Jaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...

s.

Cooperative hunting




Reef-associated roving coral grouper
Grouper
Groupers are fish of any of a number of genera in the subfamily Epinephelinae of the family Serranidae, in the order Perciformes.Not all serranids are called groupers; the family also includes the sea basses. The common name grouper is usually given to fish in one of two large genera: Epinephelus...

s (Plectropomus pessuliferus
Plectropomus pessuliferus
The roving coralgrouper is a species of fish in the Serranidae family that engages in cooperative hunting with the giant moray eel .-External links:...

), have been observed to recruit morays to join them in hunting for food. The invitation to hunt is initiated by head-shaking. The rationale for this joining of forces is the ability of morays to enter narrow crevices and flush prey from niches not accessible to groupers. This is the only known instance of interspecies cooperative hunting among fish. Cooperation on other levels, such as at cleaning station
Cleaning station
A cleaning station is a location where fish, sea turtles, hippo and other aquatic life, freshwater and marine, congregate to be cleaned.The cleaning process includes the removal of parasites from the animal's body , and can be performed by various creatures A cleaning station is a location where...

s is well-known.

Reputation


The Morays are frequently thought of as particularly vicious or ill-tempered animals. In truth, morays hide from humans in crevices and would rather flee than fight. Morays are shy and secretive, and attack humans only in self-defence or mistaken identity. Most attacks stem from disruption of a moray's burrow (to which they do react strongly), but an increasing number also occur during hand-feeding of morays by divers, an activity often used by dive companies to attract tourists. Morays have poor vision and rely mostly on their acute sense of smell, making distinguishing between fingers and held food difficult; numerous divers have lost fingers while attempting hand feedings. For this reason the hand feeding of moray eels has been banned in some locations, including the Great Barrier Reef
Great Barrier Reef
The Great Barrier Reef is the world'slargest reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,600 kilometres over an area of approximately...

. 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 pried off. While the majority are not believed to be venomous, circumstantial evidence
Circumstantial evidence
Circumstantial evidence is evidence in which an inference is required to connect it to a conclusion of fact, like a fingerprint at the scene of a crime...

 suggests that a few species may be.

Eels that have eaten certain types of toxic algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

, or more frequently that have eaten fishes that have eaten some of these algae, can cause ciguatera fish poisoning if eaten. Morays rest in crevices during the day and hunt nocturnally, although they may ensnare small fish and crustaceans that pass near them during the day.

Habitat


Moray eels are cosmopolitan
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...

, found in both tropical and temperate seas, although the largest species richness
Species richness
Species richness is the number of different species in a given area. It is represented in equation form as S.Species richness is the fundamental unit in which to assess the homogeneity of an environment. Typically, species richness is used in conservation studies to determine the sensitivity of...

 is at reefs in warm oceans. Very few species occur outside the tropics or subtropics, and the ones that do only extend marginally beyond these regions. They live at depths of up to several hundred metres, where they spend most of their time concealed inside crevices and alcoves. While several species regularly are found in brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...

, very few species can be found in freshwater, for example the freshwater moray (Gymnothorax polyuranodon) and the pink-lipped moray eel (Echidna rhodochilus).

Genera


  • Subfamily Muraeninae
    • Cirrimaxilla
    • Diaphenchelys
    • Echidna
      Echidna (genus)
      Echidna is a genus of moray eels in the family Muraenidae.-Species:In addition to the species listed below, the zebra moray has sometimes been included in Echidna.* Echidna amblyodon...

    • Enchelycore
      Enchelycore
      Enchelycore is a genus of moray eels in the family Muraenidae. Enchelycore species are generally small to medium-sized eels, most ranging from in length, with the largest being the Mosaic Moray , which reaches a length of...

    • Enchelynassa
    • Gymnomuraena
    • Gymnothorax
      Gymnothorax
      Gymnothorax is a genus of moray eels in the family Muraenidae.-Species:* Gymnothorax afer Bloch, 1795 * Gymnothorax albimarginatus...

    • Monopenchelys
    • Muraena
      Muraena
      Muraena is a genus of twelve species of large eels in the family Muraenidae.This genus is common in the Mediterranean, and highly esteemed by the ancient Romans . It is abundantly represented in tropical and subtropical seas, especially in rocky parts or on coral reefs...

    • Pseudechidna
    • Rhinomuraena
    • Scuticaria
      Scuticaria
      Scuticaria is a genus of moray eel in the family Muraenidae.-Species:* Scuticaria okinawae * Scuticaria tigrina...

    • Strophidon
  • Subfamily Uropteryginae
    • Anarchias
      Anarchias
      Anarchias is a genus of moray eels in the family Muraenidae.-Species:* Anarchias allardicei D. S. Jordan & Starks, 1906 * Anarchias cantonensis...

    • Channomuraena
      Channomuraena
      Channomuraena is a genus of moray eels in the family Muraenidae.-Species:* Channomuraena bauchotae Saldanha & Quéro, 1994* Channomuraena vittata...

    • Uropterygius
      Uropterygius
      Uropterygius is a genus of moray eels in the family Muraenidae.-Species:* Uropterygius concolor Rüppell, 1838 * Uropterygius fasciolatus...


External links