Monocled Cobra

Monocled Cobra
Monocled cobra
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Naja
Species: N. kaouthia
Binomial name
Naja kaouthia
Lesson, 1831

The monocled cobra (Naja kaouthia) is a cobra species, which is widespread across central and southern Asia. It has been assessed as Least Concern by IUCN owing 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 the species is not thought to be undergoing a significant population decline.[1]

Contents

Characteristics

The monocled cobra has an O-shaped, or monocellate hood pattern, unlike that of the Indian cobra. Coloration in young is more constant. They are olivaceous or brownish to black above with or without a yellow or orange-coloured O-shaped mark upon the hood. They have 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 of the same colour as the back, but paler. As age advances, they become paler, and when adult are brownish or olivaceous. Adult monocled cobras reach a length of 135 to 150 cm (53 to 59 in) with a tail length of 23 cm (9.1 in). Many larger specimens have been recorded, but they are rare. They have 25 to 31 scales on the neck, 19 to 21, usually 21, on the body, and 17 or 15 on the front of the vent. They have 164 to 196 Ventral scales and 43 to 58 subcaudal scales.[2]

The elongated nuchal ribs enable cobras to expand the anterior of the neck into a “hood”. When threatened, they will raise the anterior portions of their bodies, spread their hood, usually hiss loudly, and strike in an attempt to bite and defend themselves. A pair of fixed anterior fangs is present. Monocled cobras are non-spitting. Adults are a maximum of 2.3 metres (7 ft 7 in) in length. The dorsal surface may be yellow, brown, gray, or blackish and with or without ragged or clearly defined cross bands. The throat is usually immaculate and followed by a dark band. The ventral surface is the same color as the dorsal but the sub-caudals are light with dark edges.[3]

Other sources mention 27-33 scale rows around the hood, 21 ahead of mid-body, and 170 to 197 ventral scales, 46 to 61 subcaudal scales.[4]

Venom

The median lethal dose is 0.28-0.33 mg per gram of mouse body weight.[3] 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 Naja kaouthia venom is a long neurotoxin, α-cobratoxin; the minor α-neurotoxin is different from cobrotoxin in one residue.[5]

In case of intravenous injection the median lethal dose tested in mice is 0.373 mg / kg, and 0.225 mg per kg in case of intraperitoneal injection.[6][7]

Envenomation usually presents predominately 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. The presence of fang marks does not always imply that envenomation actually occurred.[8]

Distribution and habitat

Monocled cobras are distributed from India in the west through to China, Vietnam and Cambodia, also occurs in the Malay Peninsula and is native to Bangladesh, Bhutan, Myanmar, Laos, Nepal, and Thailand. They are found up to elevations of 1,000 m (3,300 ft) above sea level, and prefer habitats associated with water, such as paddy fields, swamps, and mangroves, but are also found in grasslands, shrublands, and forests, in agricultural land and human settlements, including cities.[1]

Ecology and behaviour

Monocled cobras are most active at dusk and night, but are also found basking during daytime. If disturbed, they tend to head for cover. When provoked, they raise their forebody, extending the hood and hiss.[9] They strikes only when threatened.

They prey on a wide range of animals, such as rodents, toads, lizards, birds and their eggs, sometimes even their own species.

Females lay between 16 and 33 eggs per clutch. Incubation periods range from 55 to 73 days.[10] Young are independent as soon as they hatch.

Threats

Monocled cobras are harvested for the skin trade, however, collection from the wild is minimal and not likely to be causing significant population declines.[1]

Conservation

Naja kaouthia is listed on CITES Appendix II. In places the distribution of this species coincides with protected areas, probably providing small safeguards.[1]

Taxonomic history

In 1831, Lesson first described the monocled cobra as a beautiful snake that is well distinct from the spectacled cobra, with 188 ventral scales and 53 pairs of caudal scales.[11]

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

  • In 1834, John Edward Gray published Thomas Hardwicke’s first illustration of a monocled cobra under the trinomial Naja tripudians var. fasciata.[12]
  • In 1839, Thomas Cantor described a brownish monocled cobra with numerous faint yellow transverse stripes and a hood marked with a white ring under the binomial Naja larvata, found in Bombay, Calcutta and Assam.[13]

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

  • Naja tripudians var. scopinucha 1895
  • Naja tripudians var. unicolor 1876
  • Naja tripudians var. viridis 1913
  • Naja tripudians var. sagittifera 1913

In 1940, Malcolm Arthur Smith classified the monocled cobra as a subspecies of the spectacled cobra under the trinomial Naja naja kaouthia.[14]

  • Naja kaouthia kaouthia – Deraniyagala, 1960

See also

  • Elapidae by common name
  • Elapidae by taxonomic synonyms
  • Snakebite

References

  1. ^ a b c d e Bain, R. H. (2009). "Naja kaouthia". IUCN Red List of Threatened Species. Version 2011.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/177487. 
  2. ^ Smith, M. A. (1943) Naja naja kaouthia In: The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-Region. Reptilia and Amphibia. Volume III (Serpentes). Taylor and Francis, London. Pages 428–432.
  3. ^ a b Chanhome, L., Cox, M. J., Vasaruchaponga, T., Chaiyabutra, N. Sitprija, V. (2011) Characterization of venomous snakes of Thailand. Asian Biomedicine 5 (3): 311–328.
  4. ^ "Asiatic Naja". http://pages.bangor.ac.uk/~bss166/Taxa/AsNaja.htm. 
  5. ^ 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.
  6. ^ "LD50". http://www.seanthomas.net/oldsite/ld50tot.html. 
  7. ^ "LD50 menu". http://www.kingsnake.com/toxinology/LD50/LD50men.html. 
  8. ^ Davidson, T.. "Snakebite Protocols: Summary for Human Bite by Monocellate Cobra (Naja naja kaouthia)". http://drdavidson.ucsd.edu/Portals/0/snake/Naja.htm. 
  9. ^ "Clinical Toxinology-Naja kaouthia". http://toxinology.com/fusebox.cfm?fuseaction=main.snakes.display&id=SN0040. 
  10. ^ Chanhome, L, Jintkune, P., Wilde, H., Cox, M. J. (2001) Venomous snake husbandry in Thailand. Wilderness and Environmental Medicine 12: 17–23.
  11. ^ 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). 25. Le Naja Kaouthia, Naja kaouthia, Less.. Bulletin des Sciences Naturelles et de Géologie, Tome XXV: 122.
  12. ^ Gray, J. E. (ed.) (1834) Cobra Capella. Illustrations of Indian zoology chiefly selected from the collection of Maj.-Gen. Hardwicke. Vol. II: Plate 78.
  13. ^ Cantor, T. (1839) Naja larvata. Proceedings of the Zoological Society of London. Vol. VII: 32–33.
  14. ^ Smith, M. A. (1940) Naja naja kaouthia. Records of the Indian Museum. Volume XLII: 485.

Further reading

  • Wüster, Wolfgang (1993) A century of confusion: Asiatic cobras revisited. Vivarium 4 (4): 14–18
  • Cox, Merel J. (1995) Naja kaouthia Herpetological Review 26 (3): 156–157
  • Kyi, S. W., Zug, G. R. (2003) Unusual foraging behaviour of Naja kaouthia at the Moyingye Wetlands Bird Sanctuary, Myanmar. Hamadryad 27 (2): 265–266
  • Wüster, W. Thorpe, R.S. (1991) Asiatic cobras: Systematics and snakebite. Experientia 47: 205–209
  • Wüster, W., Thorpe, R.S., Cox, M.J., Jintakune, P., Nabhitabhata, J. (1995) "Population systematics of the snake genus Naja (Reptilia: Serpentes: Elapidae) in Indochina: Multivariate morphometrics and comparative mitochondrial DNA sequencing (cytochrome oxidase I)". Journal of Evolutionary Biolology 8: 493–510
  • Wüster, W. (1996) Taxonomic changes and toxinology: Systematic revisions of the Asiatic cobras (Naja naja complex). Toxicon 34 (4): 399–406
  • Wüster, W. (1998) The cobras of the genus Naja in India Hamadryad 23 (1): 15–32

External links

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