Kidako moray

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For other uses, see Moray (disambiguation).
Kidako moray
Kidako moray.JPG

Least Concern (IUCN 3.1)
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Anguilliformes
Family: Muraenidae
Genus: Gymnothorax
Species:
G. kidako
Binomial name
Gymnothorax kidako
Synonyms
  • Gymnothorax mucifer Snyder, 1904
  • Muraena kidako Temminck & Schlegel, 1846

The Kidako moray (Gymnothorax kidako) is a species of marine fish in the family Muraenidae. There are white spots all over its brown body. It inhabits coral reefs or lagoons and could be found in tropical seas and subtropical seas such as Taiwan, Japan, and Australia. This species is diurnal, more active in the daytime compared to 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 from the Muraenidae family. The Muraenidae family consists of 16 genera including the Gymnothorax genus which the Kidako moray belongs to. The Kidako moray would not attack humans unless they are being attacked. However, due to the menacing looks of the Kidako moray and moray eels in general, they are feared by divers and snorkelers.

Description[]

The Kidako moray is a medium size fish which can reach a maximum length of 91cm.[2] The Kidako moray has a brownish color with white spots (snowflake-like) on its head, body and fins. It also has a pattern of blotches all over its body. These patterns on its body continue onto its tail. However, some of the patterns like white spots become lesser as it is closer to its tail. Around the snout and chin of Kidako moray, especially mouth angle and gill, are dark or dusky yellowish streaks.[3]

Distribution and habitat[]

Morays are commonly found in warm-temperature areas like tropical and subtropical seas.[4] Specifically, the Kidako moray is widespread throughout the western to central Ocean Pacific area from Taiwan to Polynesia, Hawaii included, and from south Japan and Korea, to New-Caledonia.[5][6] The Kidako moray usually inhabits coral reefs or lagoons. They hide in rocky bottom or reefs but they sometimes expose their head. Some of them also reside in deeper waters up to 400 meters where it has a lower temperature compared to the shallower area where most of the moray eels inhabit. In addition, morays are usually known to be nocturnal, however, observation has discovered that many of them are diurnal as not many species were active during the night.[3]

Sometimes the Kidako moray, which is quite common in some area in Japan, is used for food, so is included in some minor commercial fisheries.[7]

Dietary Habits[]

The Kidako moray is piscivorous. It consumes fish and cephalopods such as octopuses and squids to survive.[8] The dietary habits of morays could be divided into two types; piscivory and durophagy. Feeding types differ depending on the sharpness of the teeth as well as the shape or size of the jaws of moray eels.[9] The species that have the feature of long sharp caniniform teeth are more likely to consume octopus, fish, and crustaceans occasionally. On the other hand, species with molariform or short caniniform teeth tend to consume more on crustaceans.[3]

Taxonomy[]

See also: Gymnothorax

The Kidako moray belongs to the genus called Gymnothorax under the Muraenidae family with other 15 genera; including Anarchias, Channomuraena, Cirrimaxilla, Diaphenchelys, Echidna, Enchelyore, Enchelynassa, Gymnomuraena, Monopenchelys, Muraena, Pseudechidna, Rhinomuraena, Scuticaria, Strophidon, and Uropterygius.[10] According to some studies, the Muraenidae family has originated 34 to 54 million years ago in the Pacific Ocean.[4] There are approximately 200 species of moray eels split across 16 genera globally. Some species of moray eels are commonly served as a delicacy in various countries such as Portugal, Japan, and Vietnam.[11] Moreover, there are around 122 species under the Gymnothorax. They are similar to each other but have some different features and characteristics. Some of these are Gymnothorax austrinus, Gymnothorax berndti, Gymnothorax conspersus, Gymnothorax cribroris, Gymnothorax dorsalis, Gymnothorax dovii, Gymnothorax elegans, Gymnothorax fuscomaculatus, Gymnothorax gracilicauda, Gymnothorax isingteena, Gymnothorax javanicus, Gymnothorax johnsoni, Gymnothorax tile, Gymnothorax nasuta, Gymnothorax ocellatus, Gymnothorax punctatofasciatus, Gymnothorax punctatus, Gymnothorax reticularis, Gymnothorax unicolor, and Gymnothorax vagrans.[10]

Gymnothorax unicolor
Gymnothorax reticularis
Gymnothorax berndti
Gymnothorax isingteena

Relationships with humans[]

It is rare to see moray eels making unprovoked attacks on humans.[3] However, it is true that the baleful looks of moray eels frighten snorkelers and divers underwater.[3] Humans are afraid of moray eels due to their appearances. When morays eels carry out a normal respiratory movement, our focus is drawn to their protruding large jaws and dentition. They activate a protection mechanism by extending their jaws widely to the direction of the threat  when encountering an intruder. However, scenarios of moray eels attack are rare as it is mainly due to misunderstanding when divers carry out reckless acts of placing their hand into a hole in the reef.[3]

Some species of the moray eels are also able to cause wounds. Three similar cases were found during research of moray eels, and the common facts between those three were that all moray eels had serrated teeth. Researchers thought that the reason is in venom, however, no study has been found to prove this.[3]

Few death cases were reported from consuming moray eels. As moray eels are being treated as food fishes in some places, fish poisoning has the chance to happen. On Saipan island, 57 men were reported poisoned by consuming 12 inches thick moray. This caused 2 deaths and 14 of them became comatose.[3] Later in the investigation, it was found to be a typical ciguatera poisoning. This poisoning has a highly toxic compound that could show its highest level in large moray.[3]

Anatomy[]

General[]

The research established by Böhlke and Randall has shown the measurements of the body parts from a few large samples of the Kidako moray with a tapering tail. Some of the samples of the Kidako moray used for this observation can reach up to 915mm.[3] The measurements that the study expresses are proportions in terms of the total length or head length. Total length is measured from the snout tip to the tip of the tail and head length is measured from the snout tip to the posterodorsal margin of the gill opening. The length of the pre-anal is measured to the mid-anus, and the length of the snout is measured from the snout tip to the anterior margin of the eye.[3] The gill opening is where the body depth is measured, and the fin is not included for the measurement at the anus. The upper jaw length is measured until the external inner angle of the mouth from the snout tip. Except for the measurements of proportions in terms of total length or head length, the vertebral counts are also included.[3]

Its gill opening has a depth of approximately 12 to 21, anus measured before mid-body is approximately 14 to 26 in total length, and the length of the pre-anal is 2.1 to 2.5 in total length. The Kidako moray has a moderate elongate head of 7.2 to 9 in total length with a long and narrow snout that is 4.0 to 5.8 in head length. Additionally, a long jaw that is 2.0 to 2.6 in head length and small eyes above its mid-gape that are 8.4 to 14 in head length.[3] The anatomical position of its nostril is long and narrow like a tube and the posterior nostril is located above and before the anterior margin of the eye. Its branchial pores are found at the upper part and before the gill opening.[3] The dorsal fin is between the gill opening and rictus, and above the first branchial pore, the gill opening has a small size of an elliptical slit at the mid-side. There are a total of 136 to 149 vertebrae for the Kidako moray which consists of 4 to 7 vertebrae placed at the pre-dorsal and 52 to 58 vertebrae placed at the pre-anal.[3] One of the facts about the feature of moray eels is that Muraenidae is the only one that does not have pectoral fins for all the members within the order Anguilliform.[12]

Pharyngeal jaws of moray eels

Jaw[]

See also: Pharyngeal jaw and muraenidae

Moray eels have pharyngeal jaws and are categorised into two types of feeding habits; piscivorous or durophagous. The piscivorous shows longer jaws, longer curved teeth, and narrower heads compared to durophagous which have the features of shorter jaws, short blunt teeth, and larger depths of dentary.[9] The Kidako moray falls into the category of piscivorous with pharyngeal jaws. The pharyngeal jaws of the Kidako moray or moray eels in general, hold a dual-jaw system for feeding.[9] They primarily use the oral jaws to catch and assist to deliver prey into the esophagus with sharp and piercing teeth. The teeth are curved backward and pointing towards its throat to avoid prey coming back out of its mouth.[13] After they transport prey, they use the pharyngeal jaws to digest prey. During this second process, the pharyngeal jaws crush, shred, and prepare prey for digestion. This functional evolution of the moray eel has taken place through the loss of the ancestral functions. Moreover, a piscivorous is also assumed to have larger adductor muscles in the pharyngeal jaws for them to be able to carry and transport large-size fish prey.[9]

Teeth[]

The Kidako moray generally has large and uniserial teeth except for small specimens. It has six large teeth on the peripheral part of the inter-maxillary segment with the smallest pair at the most anatomical position.[3] Others include 1 to 3 tiny flanking teeth, 3 long median teeth, and 8 to 16 maxillary teeth. However, the size decreases posteriorly. On the contrary, specimens with less than 300mm have 1 to 3 inner teeth, and 4 to 14 tiny and staggered teeth on vomer which is hard to find on large specimens. Small specimens also have 2 to 4 large or 1 to 4 small teeth anteriorly. Unlike the large specimens, small specimens have 13 to 23 teeth that continue as row and become larger as it is closer to the back.[3]

Length-weight relationships[]

Gymnothorax Kidako

Another research by Loh has found that there is a relationship between the length and the weight of moray eels including the Kidako moray. In this research, the standard length of morays is measured from the tip of the closed mouth to the beginning of the anal fin rays.[11] Its head width is the width from suspensorium to suspensorium with the mouth closed. Head length is the distance from the tip of the rostrum to the neurocranium-vertebral joint and head height is measured from the bottom of the dentary directly below the eye to the top of the head above the eye.[9] The table below shows the data from 9 samples of the Kidako moray. The average standard length of the Kidako moray being observed is approximately 63.15 cm and the average weight of the Kidako moray being observed is approximately 627.25g. The length range and weight range are broad due to the combined sexes of samples.[11] However, these data are broad enough to carry out a conclusion that length and weight are correlated as the is above 0.90. The correlations between the length and the weight are also found from other moray eels such as Gymnothorax chilospilus, Gymnothorax meleagris, and Gymnothorax pictus.[11]

length (cm) weight (g)
Species sex n (sample size) min max min max
Kidako moray Female & Male 9 39.4 86.9 65.2 1189.3 0.906

[11]

Gymnothorax chilospilus
Gymnothorax meleagris
Gymnothorax pictus

References[]

  1. ^ "Gymnothorax kidako". Integrated Taxonomic Information System Database. Retrieved 6 November 2006.
  2. ^ Randall, J.E. 2005 Reef and shore fishes of the South Pacific. New Caledonia to Tahiti and the Pitcairn Islands. University of Hawaii Press, Honolulu, Hawaii. 720 p.
  3. ^ a b c d e f g h i j k l m n o p q Böhlke, Eugenia B.; Randall, John E. (2000). "A Review of the Moray eels (Angulliformes: Muraenidae) of the Hawaiian Islands, with Descriptions of Two New Species". Proceedings of the Academy of Natural Sciences of Philadelphia. 150: 203–278. ISSN 0097-3157.
  4. ^ a b Coluccia, E.; Deidda, F.; Cannas, R.; Lobina, C.; Cuccu, D.; Deiana, A. M.; Salvadori, S. (2015). "Comparative cytogenetics of six Indo-Pacific moray eels (Anguilliformes: Muraenidae) by chromosomal banding and fluorescence in situ hybridization". Journal of Fish Biology. 87 (3): 634–645. doi:10.1111/jfb.12737. ISSN 1095-8649.
  5. ^ New-CaledoniaMundy, B.C. 2005 Checklist of the fishes of the Hawaiian Archipelago. Bishop Museum Bulletins in Zoology. Bishop Mus. Bull. Zool. (6):1-704.
  6. ^ Owfi, F.; Fatemi, S. M. R.; Motallebi, A. A.; Coad, B. (2014-04-10). "Systematic review of Anguilliformes order in Iranian Museums from the Persian Gulf and Oman Sea" (PDF). Iranian Journal of Fisheries Sciences. 13 (2): 407–426.
  7. ^ Chen, H.-M., K.-T. Shao and C.T. Chen, 1994. A review of the muraenid eels (Family Muraenidae) from Taiwan with descriptions of twelve new records. Zool. Stud. 33(1):44-64.
  8. ^ Kearn, G. C. (1993). "A new species of the genus Enoplocotyle (Plateyhelminthes: Monogenea) parasitic on the skin the moray eel Gymnothorax kidako in Japan, with observations on hatching and the oncomiracidium". Journal of Zoology. 229 (4): 533–544. doi:10.1111/j.1469-7998.1993.tb02654.x. ISSN 1469-7998.
  9. ^ a b c d e Mehta, Rita S. (2009-01-01). "Ecomorphology of the Moray Bite: Relationship between Dietary Extremes and Morphological Diversity". Physiological and Biochemical Zoology. 82 (1): 90–103. doi:10.1086/594381. ISSN 1522-2152.
  10. ^ a b "ADW: Gymnothorax: CLASSIFICATION". animaldiversity.org. Retrieved 2021-05-17.
  11. ^ a b c d e Loh, K. H.; Shao, K. T.; Chen, H. M. (2011). "Length–weight relationships for 39 species of moray eel from the waters around Taiwan". Journal of Applied Ichthyology. 27 (3): 945–948. doi:10.1111/j.1439-0426.2010.01601.x. ISSN 1439-0426.
  12. ^ Mehta, Rita S.; Wainwright, Peter C. (2007-02-01). "Biting releases constraints on moray eel feeding kinematics". Journal of Experimental Biology. 210 (3): 495–504. doi:10.1242/jeb.02663. ISSN 0022-0949.
  13. ^ "Moray Eels Are Uniquely Equipped to Pack Big Prey Into Their Narrow Bodies". www.nsf.gov. Retrieved 2021-05-26.

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