Moray eel

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Moray eel
Temporal range: Late Miocene–Recent
Moray eel.jpg
Moray eel in the Maldives
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Suborder: Muraenoidei
Family: Muraenidae
Rafinesque, 1810
Subfamiles
Moray eel

Moray eels, or Muraenidae ( /ˈmɒreɪ,məˈreɪ/ ), 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 regularly seen in brackish water, and a few are found in fresh water. [2]

Contents

The English name, moray, dates back to the early 17th century, and is believed to be a derivative from Portuguese moréia, which itself derives from Latin mūrēna, in turn from Greek μύραινα, muraina; these are the Latin and Greek names of the Mediterranean moray. [3]

Anatomy

The dorsal fin 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 mostly on their highly developed sense of smell, lying in wait to ambush prey. [4]

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 (Echidna nebulosa) and zebra moray (Gymnomuraena zebra), primarily feed on crustaceans and other hard-shelled animals, and they have blunt, molar-like teeth suitable for crushing. [5]

Morays secrete a protective mucus over their smooth, scaleless skin, which in some species contains a toxin. They have much thicker skin and high densities of goblet cells 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, [6] thus making the walls of the burrow more permanent due to the glycosylation of mucins in mucus. Placement of their small, circular gills on their flanks, far behind the mouth, requires the moray to maintain a gape / gulping motion to facilitate respiration.[ clarification needed ]

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. [7] [8] [9]

Moray eel jaw anatomy Pharyngeal jaws of moray eels.svg
Moray eel jaw anatomy

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. [10] In at least one species, the California moray (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 ) to consume crustaceans, while other piscivorous genera of Muraenidae have pointed jaws and longer teeth. [11] [12] [13] These morphological patterns carry over to teeth positioned on the pharyngeal jaw. [14] [15]

Skull and pharyngeal jaws of a Gymnothorax miliaris (goldentail moray) GymnothoraxMiliarisCraniumClean.jpg
Skull and pharyngeal jaws of a Gymnothorax miliaris (goldentail moray)

Feeding-behavior

Morays are opportunistic, carnivorous predators [16] and feed primarily on smaller fish, crabs, and octopuses. [17] A spotted moray eel has been observed eating a red lionfish without harm. [18] [19] Groupers, barracudas and sea snakes are among their few known predators, making many morays (especially the larger species) apex predators in their ecosystems. [20]

Cooperative hunting

Reef-associated roving coral groupers (Plectropomus pessuliferus) have been observed recruiting giant morays 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. [21] [22] [23]

Habitat

Gymnothorax undulatus occupying a dead patch reef, located in Kona, Hawaii Moray eel in Kona.JPG
Gymnothorax undulatus occupying a dead patch reef, located in Kona, Hawaii

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 . [24] [25]

Echidna nebulosa occupying a live coral reef, located in Sabang, Philippines Spotted moray eel.jpg
Echidna nebulosa occupying a live coral reef, located in Sabang, Philippines

Within the marine realm, morays are found in shallow water nearshore areas, continental slopes, continental shelves, deep benthic habitats, and mesopelagic zones of the ocean, and in both tropical and temperate environments. [25] Tropical oceans are typically located near the equator, whereas temperate 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. [26] 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. [26]

Taxonomy

Muranidae represented on a phylogenetic tree Moray4.jpg
Muranidae represented on a phylogenetic tree

Genera

A representative structure of the Uropterygiinae sub-class Gymnomuraena marmorata Achilles 172.jpg
A representative structure of the Uropterygiinae sub-class

There are about 202 known species of moray eels, in 16 genera. These genera are in two sub-families, Muraeninae and Uropterygiinae, which are distinguished by the location of their fins. [27] In Muraeninae the dorsal fin is near the gill slits and runs down the back of the eel, and the anal fin is behind the anus. [27] In the Uropterygiinnae, both the dorsal and the anal fin are at the end of the tail. [27] 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:

Evolution

The moray eel's elongation is due to an increase in the number of vertebrae, rather than a lengthening of each individual vertebra or a substantial decrease in body depth. [28] Vertebrae have been added asynchronously between the pre-tail ("precaudal") and tail ("caudal") regions, unlike other groups of eels such as Ophicthids and Congrids. [29]

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. [30]

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; [31] [32] 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. [32] In an especially remarkable instance, 57 people in the Northern Mariana Islands were poisoned after eating just the head and half of a cooked yellow-edged moray. [33] Thus, morays are not recommended for human consumption.

Related Research Articles

<span class="mw-page-title-main">Ribbon eel</span> Species of fish

The ribbon eel, also known as the leaf-nosed moray eel or bernis eel, is a species of moray eel, the only member of the genus Rhinomuraena. The ribbon eel is found in sand burrows and reefs in the Indo-Pacific Ocean. Although generally placed in the moray eel family Muraenidae, it has several distinctive features leading some to place it in its own family, Rhinomuraenidae.

<i>Muraena</i> Genus of fishes

Muraena is a genus of twelve species of large eels in the family Muraenidae.

<i>Gymnothorax</i> Genus of fishes

Gymnothorax is a genus of fish in the family Muraenidae found in Atlantic, Indian, and Pacific Oceans. With more than 120 species, it the most speciose genus of moray eels.

<i>Echidna</i> (fish) Genus of fishes

Echidna is a genus of moray eels in the family Muraenidae.

<span class="mw-page-title-main">Kidako moray</span> Species of fish

The Kidako moray is a species of marine fish in the family Muraenidae. It inhabits coral reefs or lagoons and could be found in tropical and subtropical seas near Taiwan, Japan, and Australia. The species is diurnal, which means it is more active in the daytime than the nighttime. It is also piscivorous: it consumes fish, octopus, and squid. Other than the Kidako moray, there are about 200 species of moray eels in the Muraenidae family. The Kidako moray would not attack humans unless they are provoked. However, due to the menacing looks of the Kidako moray and moray eels in general, they are feared by divers and snorkelers.

<span class="mw-page-title-main">Zebra moray</span> Species of fish

The zebra moray is a species of marine fish in the family Muraenidae. It is the only member of the genus Gymnomuraena, though it sometimes has been included in Echidna instead.

<span class="mw-page-title-main">California moray</span> Species of fish

The California moray 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 California, and one of the few examples of a subtropical moray. They typically occupy boulder or cobble habitats up to 40 m in depth. They can attain lengths of about 5 ft (1.52 m) and are believed to live for upwards of 22–26 years. Like other morays, they have no pelvic or pectoral fins or gill covers.

<span class="mw-page-title-main">Yellow-edged moray</span> Species of fish

The yellow-edged moray, also known as yellow-margin(ed) moray, leopard moray, and speckled moray, is a moray eel of the family Muraenidae, found in the Indo-Pacific Oceans at depths to 150 m (500 ft).

<span class="mw-page-title-main">Green moray</span> Species of eel

The green moray is a moray eel of the family Muraenidae, found in the western Atlantic Ocean from Long Island, New York, Bermuda, and the northern Gulf of Mexico to Brazil, at depths down to 40 metres (130 ft). Its length is up to 2.5 metres (8.2 ft). It is the largest moray species of the tropical Atlantic and one of the largest species of moray eel known. Though it is not considered endangered, the species is particularly under-studied and estimated to be undercounted by up to 400% in single-pass visual surveys.

<span class="mw-page-title-main">Barred moray</span> Species of fish

The barred moray, also known as the banded moray, the dark-banded eel, the girdled moray, the girdled reef eel, the many banded moray eel, the ringed moray, the ringed reef moray, the striped moray and the zebra eel,) is a moray eel of the family Muraenidae. It was described by John Richardson in 1845, originally under the genus Muraena. It is a marine, tropical eel which is known from the Indo-Pacific, including the Red Sea, East Africa, the Hawaiian Islands, the Marquesan Islands, the Tuamotus Islands, the Ryukyu Islands, and the Great Barrier Reef. It dwells at a depth range of 2 to 20 metres, and leads a benthic lifestyle in reefs and shallow lagoons. Males can reach a maximum total length of 72.3 centimetres (28.5 in).

<span class="mw-page-title-main">Snowflake moray</span> Species of fish

The snowflake moray, 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 moray.

<span class="mw-page-title-main">Undulated moray</span> Species of fish

The undulated moray is a moray eel of the family Muraenidae, found in the Indo-Pacific and east-central Pacific Ocean at depths down to 30 m. Their length is up to 1.5 m.

<span class="mw-page-title-main">Fimbriated moray</span> Species of fish

The fimbriated moray, also known as dark-spotted moray or spot-face moray, is a moray eel of the family Muraenidae.

<span class="mw-page-title-main">Giant moray</span> Species of fish

The giant moray 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 length.

<span class="mw-page-title-main">Pharyngeal teeth</span> Teeth in the throat a number of other fish species

Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth.

<i>Gymnothorax miliaris</i> Species of fish

Gymnothorax miliaris, the goldentail moray, bastard eel, or conger moray, is a species of marine fish in the family Muraenidae.

<span class="mw-page-title-main">Whitemargin moray eel</span> Species of fish

The whitemargin moray or the white-edged moray, Gymnothorax albimarginatus, is a species of marine fish in the family Muraenidae.

<span class="mw-page-title-main">Indian mud moray eel</span> Species of fish

The Indian mud moray eel, is a moray eel found in the western Pacific and Indian Oceans. It was first named by Hamilton in 1822, and is also commonly known as the freshwater moray or freshwater snowflake eel.

<span class="mw-page-title-main">Barred-fin moray</span> Species of fish

The barred-fin moray or bar-tail moray is a species of marine fish in the family Muraenidae.

<span class="mw-page-title-main">Fish jaw</span>

Most bony fishes have two sets of jaws made mainly of bone. The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within the pharynx, are used to further process the food and move it from the mouth to the stomach.

References

  1. ↑ Froese, Rainer, and Daniel Pauly, eds. (2009). "Muraenidae" in FishBase. January 2009 version.
  2. ↑ Froese, Rainer; Pauly, Daniel (eds.) (2010). "Gymnothorax polyuranodon" in FishBase . January 2010 version.
  3. ↑ "Moray - definition of moray in English". Oxford Dictionaries. Archived from the original on 26 September 2016. Retrieved 11 December 2016– via oxforddictionaries.com.
    "moray". thefreedictionary.com. Retrieved 11 December 2016.
    d'Arcy, Wentworth Thompson (1947). Glossary of Greek Fishes. London, CT: Oxford University Press. pp. 162–165.
  4. ↑ "Crazy facts about the moray eel". Moray eels. Khao Lak Explorer (khaolakexplorer.com). Marine Life Guide. 16 August 2019. Retrieved 17 June 2021. Liveaboard to Similan Islands
  5. ↑ Randall, J.E. (2005). Reef and Shore Fishes of the South Pacific. University of Hawai'i Press. ISBN   0-8248-2698-1.
  6. ↑ Fishelson, L. (September 1996). "Skin morphology and cytology in marine eels adapted to different lifestyles". The Anatomical Record . 246 (1): 15–29. doi: 10.1002/(SICI)1097-0185(199609)246:1<15::AID-AR3>3.0.CO;2-E . PMID   8876820.
  7. ↑ Mehta RS, Wainwright PC (September 2007). "Raptorial jaws in the throat help moray eels swallow large prey". Nature . 449 (7158): 79–82. Bibcode:2007Natur.449...79M. doi:10.1038/nature06062. PMID   17805293. S2CID   4384411.
  8. ↑ Hopkin, Michael (5 September 2007). "Eels imitate Alien: Fearsome fish have protruding jaws in their throats to grab prey". Nature News . doi:10.1038/news070903-11. S2CID   85118599 . Retrieved 6 September 2007.
  9. ↑ "Moray eels are uniquely equipped to pack big prey into their narrow bodies". nsf.gov/news (Press release). U.S. National Science Foundation (NSF). Retrieved 11 December 2016.
  10. ↑ Mehta RS, Wainwright PC (February 2007). "Biting releases constraints on moray eel feeding kinematics". The Journal of Experimental Biology . 210 (Part 3): 495–504. doi: 10.1242/jeb.02663 . PMID   17234619.
  11. ↑ Reece JS, Bowen BW, Smith DG, Larson A (November 2010). "Molecular phylogenetics of moray eels (Muraenidae) demonstrates multiple origins of a shell-crushing jaw (Gymnomuraena, Echidna) and multiple colonizations of the Atlantic Ocean". Molecular Phylogenetics and Evolution . 57 (2): 829–35. Bibcode:2010MolPE..57..829R. doi:10.1016/j.ympev.2010.07.013. PMID   20674752.
  12. ↑ Mehta RS (January 2009). "Ecomorphology of the moray bite: relationship between dietary extremes and morphological diversity". Physiological and Biochemical Zoology. 82 (1): 90–103. doi:10.1086/594381. PMID   19053846. S2CID   19640346.
  13. ↑ Collar DC, Reece JS, Alfaro ME, Wainwright PC, Mehta RS (June 2014). "Imperfect morphological convergence: variable changes in cranial structures underlie transitions to durophagy in moray eels". The American Naturalist . 183 (6): E168–184. doi:10.1086/675810. PMID   24823828. S2CID   17433961.
  14. ↑ Böhlke, Eugenia B., ed. (1989). "Part 9: Orders Anguilliformes and Saccopharyngiformes". Fishes of the Western North Atlantic. Sears Foundation for marine research. New Haven, CT: Yale University. ISBN   978-0935868456. OCLC   30092375.
  15. ↑ Gregory, William K. (2002). Fish Skulls: A study of the evolution of natural mechanisms. Malabar, FL: Krieger Pub. ISBN   978-1575242149. OCLC   48892721.
  16. ↑ Kooser, Amanda. "See a snowflake moray eel swallow a sushi snack in an extraordinary way". CNET. Retrieved 17 June 2021.
  17. ↑ Young, Robert F.; Winn, Howard E. (February 2003). "Activity Patterns, Diet, and Shelter Site Use for Two Species of Moray Eels, Gymnothorax moringa and Gymnothorax vicinus, in Belize". Copeia. 2003 (1): 44–55. doi:10.1643/0045-8511(2003)003[0044:APDASS]2.0.CO;2. ISSN   0045-8511. S2CID   85897128.
  18. ↑ Pimiento, Catalina; Monaco, Eric; Barbour, Andrew B.; Silliman, Brian R. (2013). "Predation on Speared Red Lionfish, Pterois Volitans, by Spotted Moray, Gymnothorax Moringa". Florida Scientist. 76 (3/4): 391–394. ISSN   0098-4590. JSTOR   24321994.
  19. ↑ June 2021, Mindy Weisberger-Senior Writer 10 (10 June 2021). "These eels can swallow prey on land, thanks to extendable jaws in their throats". livescience.com. Retrieved 17 June 2021.{{cite web}}: CS1 maint: numeric names: authors list (link)
  20. ↑ "Moray Eel - Facts and Beyond". Biology Dictionary. 10 July 2020. Retrieved 17 June 2021.
  21. ↑ In the December 2006 issue of the journal Public Library of Science Biology, a team of biologists announced the discovery of interspecies cooperative hunting involving morays. The biologists, who were engaged in a study of Red Sea cleaner fish (fish that enter the mouths of other fish to rid them of parasites), made the discovery.An Amazing First: Two Species Cooperate to Hunt | LiveScience
  22. ↑ Bshary R, Hohner A, Ait-el-Djoudi K, Fricke H (December 2006). "Interspecific communicative and coordinated hunting between groupers and giant moray eels in the Red Sea". PLOS Biology. 4 (12): e431. doi: 10.1371/journal.pbio.0040431 . PMC   1750927 . PMID   17147471.
  23. ↑ Vail A.L., Manica A., Bshary R., Referential gestures in fish collaborative hunting, in Nature Communications, vol. 4, 2013.
  24. ↑ Ebner, Brendan C.; Fulton, Christopher J.; Donaldson, James A.; Schaffer, Jason (2015). "Distinct habitat selection by freshwater morays in tropical rainforest streams". Ecology of Freshwater Fish. 25 (2): 329–335. doi: 10.1111/eff.12213 . ISSN   0906-6691.
  25. 1 2 Tsukamoto, Katsumi; Watanabe, Shun; Kuroki, Mari; Aoyama, Jun; Miller, Michael J. (2014). "Freshwater habitat use by a moray eel species, Gymnothorax polyuranodon, in Fiji shown by otolith microchemistry". Environmental Biology of Fishes. 97 (12): 1377–1385. Bibcode:2014EnvBF..97.1377T. doi:10.1007/s10641-014-0228-9. ISSN   0378-1909. S2CID   7596020.
  26. 1 2 Young, Robert F.; Winn, Howard E.; Montgomery, W. L. (2003). "Activity Patterns, Diet, and Shelter Site Use for Two Species of Moray Eels, Gymnothorax moringa and Gymnothorax vicinus, in Belize". Copeia. 2003 (1): 44–55. doi:10.1643/0045-8511(2003)003[0044:APDASS]2.0.CO;2. ISSN   0045-8511. S2CID   85897128.
  27. 1 2 3 Reece, Joshua (January 2010). "Phylogenetics and phylogeography of moray eels (Muraenidae)". Washington University Open Scholarship– via openscholarship.wustl.edu.
  28. ↑ Mehta, Rita S.; Reece, Joshua S. (July 2013). "Evolutionary history of elongation and maximum body length in moray eels (Anguilliformes: Muraenidae)". Biological Journal of the Linnean Society. 109 (4): 861–875. doi: 10.1111/bij.12098 .
  29. ↑ Mehta RS, Ward AB, Alfaro ME, Wainwright PC (December 2010). "Elongation of the body in eels". Integrative and Comparative Biology. 50 (6): 1091–105. doi: 10.1093/icb/icq075 . PMID   21558261.
  30. ↑ Maddox, Mike. "Morays!". TFH Magazine. Retrieved 29 August 2018.
  31. ↑ Chan TY (April 2016). "Characteristic Features and Contributory Factors in Fatal Ciguatera Fish Poisoning--Implications for Prevention and Public Education". The American Journal of Tropical Medicine and Hygiene. 94 (4): 704–9. doi:10.4269/ajtmh.15-0686. PMC   4824207 . PMID   26787145.
  32. 1 2 Chan TY (June 2017). "Regional Variations in the Risk and Severity of Ciguatera Caused by Eating Moray Eels". Toxins. 9 (7): 201. doi: 10.3390/toxins9070201 . PMC   5535148 . PMID   28672845.
  33. ↑ Khlentzos, Constantine T. (1 September 1950). "Seventeen Cases of Poisoning Due to Ingestion of an Eel, Gymnothorax Flavimarginatus 1". The American Journal of Tropical Medicine and Hygiene. s1-30 (5): 785–793. doi:10.4269/ajtmh.1950.s1-30.785. ISSN   0002-9637. PMID   14771403.

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