Monocled cobra

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Monocled cobra
Monocled cobra (cropped).jpg
Monocled cobra
CITES Appendix II (CITES) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Naja
Species:
N. kaouthia
Binomial name
Naja kaouthia
Lesson, 1831
South East Asia location-Naja-kaouthia.svg
Naja kaouthia distribution

The monocled cobra (Naja kaouthia), also called monocellate cobra and Indian spitting cobra, is a venomous cobra species widespread across South and Southeast Asia and listed as Least Concern on the IUCN Red List. [1]

Contents

Taxonomy

The scientific name Naja kaouthia was proposed by René Lesson in 1831, when he described the monocled cobra as a beautiful snake that is distinct from the spectacled cobra, with 188 ventral scales and 53 pairs of caudal scales. [2]

Since then, several monocled cobras were described under different scientific names:

Several varieties of monocled cobras were described under the binomial Naja tripudians between 1895 and 1913:

In 1940, Malcolm Arthur Smith classified the monocled cobra as a subspecies of the spectacled cobra under the trinomial Naja naja kaouthia. [5] Reclassification in the 1990s further distinguished Naja kaouthia from Naja siamensis , a name commonly used in older toxinological research. [6]

Phylogenetic studies of Naja kaouthia in Thailand have demonstrated surprising variation, with one population resulting in the species becoming paraphyletic with other Asiatic cobras. [7]

Characteristics

Characteristic monocle pattern on hood Hooded Cobra - Howrah 2017-12-25 5748.JPG
Characteristic monocle pattern on hood

The monocled cobra has an O-shaped, or monocellate hood pattern, unlike that of the Indian cobra, which has the "spectacle" pattern (two circular ocelli connected by a curved line) on the rear of its hood. The elongated nuchal ribs enable a cobra to expand the anterior of the neck into a “hood”. Coloration in the young is more constant. The dorsal surface may be yellow, brown, gray, or blackish, with or without ragged or clearly defined cross bands. It can be olivaceous or brownish to black above with or without a yellow or orange-colored, O-shaped mark on the hood. It has a black spot on the lower surface of the hood on either side, and one or two black cross-bars on the belly behind it. The rest of the belly is usually the same color as the back, but paler. As age advances, the snake becomes paler, wherein the adult is brownish or olivaceous. A pair of fixed anterior fangs is present. The largest fang recorded measured 6.78 mm (0.678 cm). Fangs are moderately adapted for spitting. [8]

Adult monocled cobras reach a length of 1.35 to 1.5 m (4.4 to 4.9 ft) with a tail length of 23 cm (9.1 in). Many larger specimens have been recorded, but they are rare. Adults can reach a maximum of 2.3 m (7.5 ft) in length. [9] [10]

Scalation

The monocled cobra has 25 to 31 scales on the neck, 19 to 21 on the body, and 17 or 15 on the front of the vent. It has 164 to 197 ventral scales and 43 to 58 subcaudal scales. [9] It typically has more than one cuneate scale on each side. The shape of the frontal scale is short and square. Ventrals in males range from 170 to 192, in females from 178 to 197. Subcaudals in males range from 48 to 61, in females from 46 to 59. [8]

Distribution and habitat

The monocled cobra is distributed from India in the west through to China, Vietnam and Cambodia. It also occurs on the Malay Peninsula and is native to West Bengal, Bangladesh, Bhutan, Myanmar, Laos, Nepal, and Thailand. It can adapt to a range of habitats, from natural to anthropogenically impacted environments. It prefer habitats associated with water, such as paddy fields, swamps and mangroves, but lives also in grasslands, shrublands, forests, agricultural land at elevations of up to 1,000 m (3,300 ft) and human settlements including cities. [1]

Ecology and behaviour

Monocled cobras are terrestrial and most active at dusk. In rice-growing areas, they hide in rodent burrows in the dykes between fields and have become semi-aquatic in this type of habitat. Juveniles feed mostly on amphibians whereas adults prey on small mammals, snakes and fish. When disturbed they prefer to escape. [8] However, when threatened they will raise the anterior portions of their bodies, spread their hood, usually hiss loudly, and strike in attempt to bite and defend themselves. [10]

They are often found in tree holes and areas where rodents are plentiful. [11]

Some populations of the monocled cobra have the ability to spit venom, earning them the name "Indian spitting cobra". [12] [13]

Reproduction

This is an oviparous species. Females lay 16 to 33 eggs per clutch. Incubation periods range from 55 to 73 days. [14] Egg-laying takes place January through March. The females usually stay with the eggs. Some collaboration between males and females has been reported in Naja naja x Naja kaouthia - hybrids. [8]

Conservation status

The monocled cobra is listed on CITES Appendix II and has been assessed as Least Concern on the IUCN Red List due to its large distribution, tolerance of a broad range of habitats including anthropogenically altered environments, and its reported abundance. No major threats have been reported, and it is not thought to be undergoing a significant population decline. Monocled cobras are harvested for the wildlife trade, however, collection from the wild is minimal and not likely to cause significant population declines. [1]

Venom

The venom of the monocled cobra from three different localities were reported to exhibit different intravenous and subcutaneous median lethal dose: Thailand, 0.18-0.22 µg/g; Malaysia, 0.90-1.11 µg/g; and Vietnam, 0.90-1.00 µg/g, of mouse body weight. These results reflect the distinct difference in the lethal potency of the monocled cobra and response to antivenom neutralization. [15] The major toxic components in cobra venoms are postsynaptic neurotoxins, which block the nerve transmission by binding specifically to the nicotinic acetylcholine receptor, leading to flaccid paralysis and even death by respiratory failure. The major α-neurotoxin in the monocled cobra's venom is a long neurotoxin, α-cobratoxin; the minor α-neurotoxin is different from cobrotoxin in one residue. [16] The neurotoxins of this particular species are weak. [17] The venom of this species also contains myotoxins and cardiotoxins. [18] [19]

In case of intravenous injection the LD50 tested in mice is 0.373 mg/kg, and 0.225 mg/kg in case of intraperitoneal injection. [20] The average venom yield per bite is approximately 263 mg dry weight. [21]

The monocled cobra causes the highest fatality due to snake venom poisoning in Thailand. [22] Envenomation usually presents predominantly with extensive local necrosis and systemic manifestations to a lesser degree. Drowsiness, neurological and neuromuscular symptoms will usually manifest earliest; hypotension, flushing of the face, warm skin, and pain around bite site typically manifest within one to four hours following the bite; paralysis, ventilatory failure or death could ensue rapidly, possibly as early as 60 minutes in very severe cases of envenomation. However, the presence of fang marks does not always imply that envenomation actually occurred. [23]

See also

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References

  1. 1 2 3 4 5 Stuart, B.; Wogan, G. (2012). "Naja kaouthia". IUCN Red List of Threatened Species . 2012: e.T177487A1488122. doi: 10.2305/IUCN.UK.2012-1.RLTS.T177487A1488122.en . Retrieved 29 January 2022.
  2. ↑ Lesson, R.-P. (1831). "Catalogue des Reptiles qui font partie d'une Collection zoologique recueillie dans l'Inde continental ou en Afrique, et apportée en France par M. Lamare-Piqout. Catalogue dressé (juillet 1831)". Bulletin des Sciences Naturelles et de Géologie (XXV): 119–123.
  3. ↑ Gray, J. E. (1834). "Cobra Capella". Illustrations of Indian zoology chiefly selected from the collection of Maj.-Gen. Hardwicke. Vol. II. p. Plate 78.
  4. ↑ Cantor, T. (1839). "Naja larvata". Proceedings of the Zoological Society of London. VII: 32–33.
  5. ↑ Smith, M. A. (1940). "Naja naja kaouthia". Records of the Indian Museum. XLII: 485.
  6. ↑ Wüster, W. (1996). "Taxonomic changes and toxinology: Systematic revisions of the Asiatic cobras (Naja naja species complex)". Toxicon. 34 (4): 399–406. doi:10.1016/0041-0101(95)00139-5. PMID   8735239.
  7. ↑ Ratnarathorn, N.; Harnyuttanakorn, P.; Chanhome, L.; Evans, S. E.; Day, J. J. (2019). "Geographical differentiation and cryptic diversity in the monocled cobra, Naja kaouthia (Elapidae), from Thailand". Zoologica Scripta. 48 (6): 711–726. doi:10.1111/zsc.12378. S2CID   201199120.
  8. 1 2 3 4 Wüster, W. (1998). "The cobras of the genus Naja in India" (PDF). Hamadryad. 23 (1): 15–32.
  9. 1 2 Smith, M. A. (1943). "Naja naja kaouthia". The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-Region. Reptilia and Amphibia. Vol. III (Serpentes). London: Taylor and Francis. pp. 428–432.
  10. 1 2 Chanhome, L.; Cox, M. J.; Vasaruchaponga, T.; Chaiyabutra, N. S. (2011). "Characterization of venomous snakes of Thailand". Asian Biomedicine. 5 (3): 311–328.
  11. ↑ "Naja kaouthia: General Details and Information". WCH Clinical Toxinology Resource. University of Adelaide. Retrieved 3 February 2012.
  12. ↑ Wuster, Wolfgang; Thorpe, Roger S. (1992). "Dentitional phenomena in cobra revisited: spitting and fang structure in the Asiatic species of Naja (Serpentes: Elapidae)" (PDF). Herpetologica. 48 (4): 424–434.
  13. ↑ Santra, Vishal; Wüster, Wolfgang (2017). "Naja kaouthia behavior/spitting" (PDF). Herpetological Review. 48 (2): 455.
  14. ↑ Chanhome, L; Jintkune, P.; Wilde, H.; Cox, M. J. (2001). "Venomous snake husbandry in Thailand". Wilderness and Environmental Medicine. 12 (1): 17–23. doi: 10.1580/1080-6032(2001)012[0017:vshit]2.0.co;2 . PMID   11294550.
  15. ↑ Tan, K.Y.; Tan, C.H.; Fung, S.Y.; Tan, N.H. (2015). "Venomics, lethality and neutralization of Naja kaouthia (monocled cobra) venoms from three different geographical regions of Southeast Asia". Journal of Proteomics. 120: 105–125. doi:10.1016/j.jprot.2015.02.012. PMID   25748141.
  16. ↑ Wei, J.-F.; Lü, Q.-M.; Jin, Y.; Li, D.-S.; Xiong, Y.-L.; Wang, W.-Y. (2003). "α-Neurotoxins of Naja atra and Naja kaouthia Snakes in Different Regions". Acta Biochimica et Biophysica Sinica. 35 (8): 683–688. PMID   12897961.
  17. ↑ Ogay, A.; Rzhevskya, D.I.; Murasheva, A.N.; Tsetlinb, V.I.; Utkin, Y.N. (2005). "Weak neurotoxin from Naja kaouthia cobra venom affects haemodynamic regulation by acting on acetylcholine receptors". Toxicon. 45 (1): 93–99. doi:10.1016/j.toxicon.2004.09.014. PMID   15581687.
  18. ↑ Mahanta, M.; Mukherjee, A.K. (2001). "Neutralisation of lethality, myotoxicity and toxic enzymes of Naja kaouthia venom by Mimosa pudica root extracts". Journal of Ethnopharmacology. 75 (1): 55–60. doi:10.1016/S0378-8741(00)00373-1. PMID   11282444.
  19. ↑ Fletcher, J. E.; Jiang, M.-S.; Gong, Q.-H.; Yudkowsky, M.L.; Wieland, S.J. (1991). "Effects of a cardiotoxin from Naja kaouthia venom on skeletal muscle: Involvement of calcium-induced calcium release, sodium ion currents and phospholipases A2 and C". Toxicon. 29 (12): 1489–1500. doi:10.1016/0041-0101(91)90005-C. PMID   1666202.
  20. ↑ Fry, B.G. "LD50 Menu". Australian Venom Research Unit. University of Queensland. Archived from the original on 13 April 2012. Retrieved 25 December 2011.
  21. ↑ Engelmann, W.-E. (1981). Snakes: Biology, Behavior, and Relationship to Man. Leipzig; English version NY, USA: Leipzig Publishing; English version published by Exeter Books (1982). p. 51. ISBN   978-0-89673-110-3.
  22. ↑ Pratanaphon, R.; Akesowan, S.; Khow, O.; Sriprapat, S.; Ratanabanangkoon, K. (1997). "Production of highly potent horse antivenom against the Thai cobra (Naja kaouthia)". Vaccine. 15 (14): 1523–1528. doi:10.1016/S0264-410X(97)00098-4. PMID   9330463.
  23. ↑ Davidson, T. "Snakebite Protocols: Summary for Human Bite by Monocellate Cobra (Naja naja kaouthia)". Archived from the original on 2012-12-03. Retrieved 2011-11-10.

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