Moray eels, or Muraenidae (), are a
family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
of
eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively
marine
Marine is an adjective meaning of or pertaining to the sea or ocean.
Marine or marines may refer to:
Ocean
* Maritime (disambiguation)
* Marine art
* Marine biology
* Marine debris
* Marine habitats
* Marine life
* Marine pollution
Military ...
, but several species are regularly seen in
brackish water
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
, and a few are found in
fresh water
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does incl ...
.
The English name, from the early 17th century, derives from
Portuguese , which itself derives from
Latin
Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
, in turn from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
, ; these are the Latin and Greek names of the
Mediterranean moray.
Anatomy
The
dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...
extends from just behind the head along the back and joins seamlessly with the
caudal
Caudal may refer to:
Anatomy
* Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism
* Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into the ...
and
anal fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...
s. Most species lack
pectoral and
pelvic fin
Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods.
Structure and function Structure
In actinopterygians, the pelvic fin consists of two ...
s, adding to their serpentine appearance. Their eyes are rather small; morays rely mostly on their highly developed sense of smell, lying in wait to ambush prey.
The body is generally patterned. In some species, the inside of the mouth is also patterned. Their jaws are wide, framing a protruding snout. Most possess large teeth used to tear flesh or grasp slippery prey. A relatively small number of species, for example the
snowflake moray
The snowflake moray (''Echidna nebulosa''), also known as the clouded moray among many vernacular names, is a species of marine eel of the family Muraenidae. It has blunt teeth ideal for its diet of crustaceans, a trait it shares with the zebra m ...
(''Echidna nebulosa'') and
zebra moray (''Gymnomuraena zebra''), primarily feed on
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...
s and other hard-shelled animals, and they have blunt,
molar-like teeth suitable for crushing.
[Randall, J. E. (2005). ''Reef and Shore Fishes of the South Pacific.'' University of Hawai'i Press. ]
Morays secrete a protective
mucus
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It ...
over their smooth, scaleless skin, which in some species contains a toxin. They have much thicker skin and high densities of
goblet cell
Goblet cells are simple columnar epithelial cells that secrete gel-forming mucins, like mucin 5AC. The goblet cells mainly use the merocrine method of secretion, secreting vesicles into a duct, but may use apocrine methods, budding off their s ...
s in the
epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rel ...
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 is the reaction in which a carbohydrate (or ' glycan'), i.e. a glycosyl donor, is attached to a hydroxyl or other functional group of another molecule (a glycosyl acceptor) in order to form a glycoconjugate. In biology (but not al ...
of
mucins
Mucins () are a family of high molecular weight, heavily glycosylated proteins (glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in most ...
in mucus. Their small, circular
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they ar ...
s, located on the flanks far posterior to the mouth, require the moray to maintain a gap to facilitate
respiration.
Jaw
The
pharyngeal jaws of morays are located farther back in the head and closely resemble the oral jaws (complete with tiny "teeth"). When feeding, morays launch these jaws into the mouth cavity, where they grasp prey and transport it into the throat. Moray eels are the only known animals that use pharyngeal jaws to actively capture and restrain prey in this way.
In addition to the presence of pharyngeal jaws, morays' mouth openings extend far back into the head, compared to fish which feed using suction. In the action of lunging at prey and biting down, water flows out the posterior side of the mouth opening, reducing waves in front of the eel which would otherwise displace prey. Thus, aggressive predation is still possible even with reduced bite times. In at least one species, the
California moray
The California moray (''Gymnothorax mordax'') is a moray eel of the family Muraenidae, found in the eastern Pacific from just north of Santa Barbara to Santa Maria Bay in Baja California. They are the only species of moray eel found off Califor ...
(''Gymnothorax mordax''), teeth in the roof of the mouth are able to fold down as prey slides backwards, thus preventing the teeth from breaking and maintaining a hold on prey as it is transported to the throat.
Differing shapes of the jaw and teeth reflect the respective diets of different species of moray eel. Evolving separately multiple times within the Muraenidae family, short, rounded jaws and molar-like teeth allow
durophagous eels (e.g. zebra moray and genus ''
Echidna
Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...
'') to consume crustaceans, while other
piscivorous genera of Muraenidae have pointed jaws and longer teeth. These morphological patterns carry over to teeth positioned on the pharyngeal jaw.
Feeding-behavior
Morays are opportunistic,
carnivorous
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other ...
predators and feed primarily on smaller fish, crabs, and
octopus
An octopus ( : octopuses or octopodes, see below for variants) is a soft-bodied, eight- limbed mollusc of the order Octopoda (, ). The order consists of some 300 species and is grouped within the class Cephalopoda with squids, cuttlefish, ...
es. A
spotted moray eel
The spotted moray eel (''Gymnothorax isingteena'') is a moray eel found in coral reefs in the Pacific and Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's su ...
has been observed eating a
red lionfish without harm.
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" ...
s,
barracuda
A barracuda, or cuda for short, is a large, predatory, ray-finned fish known for its fearsome appearance and ferocious behaviour. The barracuda is a saltwater fish of the genus ''Sphyraena'', the only genus in the family Sphyraenidae, which ...
s and
sea snake
Sea snakes, or coral reef snakes, are elapid snakes that inhabit marine environments for most or all of their lives. They belong to two subfamilies, Hydrophiinae and Laticaudinae. Hydrophiinae also includes Australasian terrestrial snakes, w ...
s are among their few known
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill t ...
s, making many morays (especially the larger species)
apex predators in their ecosystems.
Cooperative hunting
Reef-associated
roving coral grouper
The roving coral grouper (''Plectropomus pessuliferus''), also known as the spotted coral grouper, is a species of marine ray-finned fish, a grouper from the subfamily Epinephelinae which is part of the family Serranidae, which also includes the ...
s (''Plectropomus pessuliferus'') have been observed recruiting
giant moray
The giant moray (''Gymnothorax javanicus'') is a species of moray eel and a species of marine fish in the family Muraenidae. In terms of body mass, it is the largest moray eel; however, the slender giant moray is the largest in terms of body le ...
s to help them hunt. The invitation to hunt is initiated by head-shaking. This style of hunting may allow morays to
flush prey from niches not accessible to groupers.
Habitat
The moray eel can be found in both fresh and
saltwater habitats. The vast majority of species are strictly marine, never entering freshwater. Of the few species known to live in freshwater, the most well-known is ''
Gymnothorax polyuranodon''.
Within the marine realm, morays are found in
shallow water nearshore areas,
continental slopes,
continental shelves
A continental shelf is a portion of a continent that is submerged under an area of relatively shallow water, known as a shelf sea. Much of these shelves were exposed by drops in sea level during glacial periods. The shelf surrounding an island ...
,
deep benthic habitats, and
mesopelagic zone
The mesopelagic zone ( Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins a ...
s of the ocean, and in both tropical and temperate environments.
Tropical
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
oceans are typically located near the equator, whereas
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout ...
oceans are typically located away from the equator. Most species are found in tropical or subtropical environments, with only a few species (
yellow moray) found in temperate ocean environments.
Although the moray eel can occupy both tropical oceans and temperate oceans, as well as both freshwater and saltwater, the majority of moray eels occupy warm saltwater environments, which contain
reefs.
Within the tropical oceans and temperate oceans, the moray eel occupies shelters, such as dead patch reefs and coral rubble rocks, and less frequently occupies live coral reefs.
Taxonomy
Genera
There are currently around 202 known species of moray eels, divided among 16 genera. These genera fall into the two sub-families of Muraeninae and
Uropterygiinae
Uropterygiinae is a subfamily of moray eel
Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are re ...
, which can be distinguished by the location of their fins.
In Muraeninae the dorsal fin is found near the
gill slits and runs down the back of the eel, while the anal fin is behind the anus.
The Uropterygiinnae, on the other hand, are defined by both their dorsal and anal fin being located at the end of their tails.
Though this distinction can be seen between the two sub-families, there are still many varieties of genera within Muraeninae and Uropterygiinae. Of these, the genus ''
Gymnothorax'' is by far the broadest, including more than half of the total number of species.
List of genera according to the
World Register of Marine Species :
* Subfamily Muraeninae
** Genus ''
Diaphenchelys'' — 1 species
** Genus ''
Echidna
Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...
'' — 11 species
** Genus ''
Enchelycore'' — 13 species
** Genus ''
Enchelynassa'' — 1 species
** Genus ''
Gymnomuraena'' — 1 species
** Genus ''
Gymnothorax'' — 125 species
** Genus ''
Monopenchelys'' — 1 species
** Genus ''
Muraena
''Muraena'' is a genus of twelve species of large eels in the family Muraenidae.
This genus is common in the Mediterranean, and is abundantly represented in tropical and subtropical seas, especially in rocky parts or on coral reefs. In the majo ...
'' — 10 species
** Genus ''
Pseudechidna'' — 1 species
** Genus ''
Rhinomuraena'' — 1 species
** Genus ''
Strophidon
''Strophidon'' is a genus of eels in the family Muraenidae. The genus has a wide distribution throughout the Pacific and Indian Oceans where they mostly inhabit the benthic zone.
Species
There are currently 2 described species in ''Strophidon ...
'' — 1 species
* Subfamily
Uropterygiinae
Uropterygiinae is a subfamily of moray eel
Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are re ...
** Genus ''
Anarchias
''Anarchias'' is a genus of moray eels in the family Muraenidae
Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but s ...
'' — 11 species
** Genus ''
Channomuraena'' — 2 species
** Genus ''
Cirrimaxilla'' — 1 species
** Genus ''
Scuticaria'' — 2 species
** Genus ''
Uropterygius
''Uropterygius'' is a genus of moray eels in the family Muraenidae.
Species
There are currently 20 recognized species in this genus:
* '' Uropterygius concolor'' Rüppell, 1838 (Unicolor snake moray)
* '' Uropterygius fasciolatus'' ( Regan, 19 ...
'' — 20 species
File:TakamayuUBf.jpg, ''Anarchias seychellensis
''Anarchias seychellensis'' is a moray eel found in coral reefs
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral ...
''
File:FMIB 47184 Gymomuraena vittata, from Cuba.jpeg, '' Channomuraena vittata''
File:Echidna nebulosa Réunion.jpg, Snowflake moray
The snowflake moray (''Echidna nebulosa''), also known as the clouded moray among many vernacular names, is a species of marine eel of the family Muraenidae. It has blunt teeth ideal for its diet of crustaceans, a trait it shares with the zebra m ...
(''Echidna nebulosa'')
File:Enchelycore schismatorhynchus.JPG, '' Enchelycore schismatorhynchus''
File:FMIB 42381 Enchelynassa vinolentus (Jordan & Evermann).jpeg, Viper moray (''Enchelynassa canina'')
File:Gymnomuraena zebra by NPS.jpg, Zebra moray (''Gymnomuraena zebra'')
File:Laced Moray.jpg, Laced moray (''Gymnothorax favagineus'')
File:Gymnothorax rueppelliae Réunion.JPG, '' Gymnothorax rueppelliae''
File:Monopenchelys acuta - pone.0010676.g012.png, '' Monopenchelys acuta''
File:Muraena helena swimming .jpg, Mediterranean moray (''Muraena helena'')
File:Pseudechidna brummer).JPG, White ribbon eel (''Pseudechidna brummeri'')
File:Ribbon Moray (Rhinomuraena quaesita) (6052858389).jpg, Ribbon eel
The ribbon eel (''Rhinomuraena quaesita''), also known as the leaf-nosed moray eel or bernis eel, is a species of moray eel, the only member of the genus ''Rhinomuraena''. What is now known as ''R. quaesita'' also includes the former ''R. ambo ...
(R''hinomuraena quaesita'')
File:Scuticaria tigrina.jpg, ''Scuticaria tigrina
''Scuticaria tigrina'' is a moray eel
Moray eels, or Muraenidae (), are a family of eels whose members are found worldwide. There are approximately 200 species in 15 genera which are almost exclusively marine, but several species are regularl ...
''
File:Strophidon sathete.jpg, Slender giant moray (''Strophidon sathete'')
File:Uropterygius xanthopterus - 2.JPG, '' Uropterygius xanthopterus''
File:Kidako moray.JPG, Kidako moray (''Gymnothorax kidako'')
Evolution
Elongation
The moray eel's elongation is due to an increase in the number of
vertebrae
The spinal column, a defining synapomorphy shared by nearly all vertebrates, Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristi ...
, rather than a lengthening of each individual vertebra or a substantial decrease in body depth.
Vertebrae have been added asynchronously between the pre-tail ("precaudal") and tail ("caudal") regions, unlike other groups of eels such as Ophicthids and Congrids.
Relationship with humans
Aquarium trade
Several moray species are popular among aquarium hobbyists for their hardiness, flexible diets, and disease resistance. The most commonly traded species are the snowflake, zebra and goldentail moray (''
Gymnothorax miliaris''). Several other species are occasionally seen, but are more difficult to obtain and can command a steep price on the market.
Food poisoning
Moray eels, particularly the giant moray (''Gymnothorax javanicus'') and yellow-edged moray (''
G. flavimarginatus''), are known to accumulate high levels of
ciguatoxins, unlike other reef fish;
if consumed by humans,
ciguatera fish poisoning may result. Ciguatera is characterised by neurological, gastrointestinal, and cardiovascular problems that may persist for days after eating tainted fish. In morays, the toxins are most concentrated in the liver.
In an especially remarkable instance, 57 people in the
Northern Mariana Islands
The Northern Mariana Islands, officially the Commonwealth of the Northern Mariana Islands (CNMI; ch, Sankattan Siha Na Islas Mariånas; cal, Commonwealth Téél Falúw kka Efáng llól Marianas), is an unincorporated territory and commonw ...
were poisoned after eating just the head and half of a cooked yellow-edged moray.
Thus, morays are not recommended for human consumption.
References
Further reading
* Gross, Miriam J.. The Moray Eel. United States: Rosen Publishing Group's PowerKids Press, 2005.
* Purser, Phillip. Keeping Moray Eels in Aquariums. United States: T.F.H., 2005.
* Didier, Dominique A.. Moray Eel. United States: Cherry Lake Publishing, 2014.
* Goldish, Meish. Moray Eel: Dangerous Teeth. United Kingdom: Bearport Publishing, 2009.
External links
Moray Eels Grab Prey With ''Alien'' Jaws* Smith, J.L.B. 1962
The moray eels of the Western Indian Ocean and the Red Sea. Ichthyological Bulletin; No. 23 Department of Ichthyology, Rhodes University, Grahamstown, South Africa.
{{DEFAULTSORT:Moray Eel
*
Articles containing video clips
Extant Miocene first appearances
Taxa named by Constantine Samuel Rafinesque