Naja

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Naja
Indiancobra.jpg
Naja naja, Indian cobra
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Elapidae
Genus: Naja
Laurenti, 1768

Naja is a genus of venomous elapid snakes known as cobras. Several other genera include species commonly called cobras (for example the king cobra, Ophiophagus hannah and the rinkhals, or ring-necked spitting cobra, Hemachatus haemachatus), but of all the snakes known by that name, members of the genus Naja are the most widespread and the most widely recognized as cobras. Various species occur in regions throughout Africa, Southwest Asia, South Asia and Southeast Asia.

Until recently the genus Naja had 20 to 22 species, but it has undergone several taxonomic revisions in recent years, so sources vary greatly.[1] There is however wide support for a 2009 revision[2] that synonymised the genera Boulengerina and Paranaja with Naja. According to that revision the genus Naja now includes 28 species.

Naja naja, Indian cobra

Etymology[edit]

The origin of this genus name is from the Sanskrit nāga (with a hard "g") meaning "snake". Some hold that the Sanskrit word is cognate with English "snake", Germanic: *snēk-a-, Proto-IE: *(s)nēg-o-,[3] but this is unlikely. Mayrhofer calls this etymology "unglaubhaft ", "not credible", and suggests a more plausible etymology connecting it with Sanskrit nagna, "hairless, naked".[4]

Taxonomy[edit]

Naja
(Naja)

Naja (Naja) naja





Naja (Naja) kaouthia



Naja (Naja) atra





Naja (Naja) mandalayensis



Naja (Naja) siamensis



Naja (Naja) sputatrix






(Afronaja)


Naja (Afronaja) pallida



Naja (Afronaja) nubiae





Naja (Afronaja) katiensis




Naja (Afronaja) nigricollis




Naja (Afronaja) ashei




Naja (Afronaja) mossambica



Naja (Afronaja) nigricincta








(Boulengerina)

Naja (Boulengerina) multifasciata



Naja (Boulengerina) christyi





Naja (Boulengerina) christyi



Naja (Boulengerina) annulata




Naja (Boulengerina) melanoleuca




(Uraeus)

Naja (Uraeus) nivea




Naja (Uraeus) senegalensis




Naja (Uraeus) haje



Naja (Uraeus) arabica





Naja (Uraeus) annulifera



Naja (Uraeus) anchietae








Description[edit]

Different Naja species vary in length and most are relatively slender-bodied snakes. Most species are capable of attaining lengths of 1.84 m (6.0 ft). Maximum lengths for some of the larger species of cobra are around 3.1 m (10 ft), with the forest cobra arguably being the longest species.[5] All have a characteristic ability to raise the front quarters of their bodies off the ground and flatten their necks to appear larger to a potential predator.

Venom[edit]

All species in the genus Naja are capable of delivering a fatal bite to a human. Most species have strongly neurotoxic venom, which attacks the nervous system, causing paralysis, but many also have cytotoxic features which causes swelling and necrosis, and has a significant anticoagulant effect. Some also have cardiotoxic components to their venom.

Several Naja species, referred to as spitting cobras, have a specialized venom delivery mechanism, in which their front fangs, instead of releasing venom through the tips (similar to a hypodermic needle), have a rifled opening in the front surface which allows the snake to propel the venom out of the mouth. While typically referred to as "spitting", the action is more like squirting. The range and accuracy with which they can shoot their venom varies from species to species, but it is used primarily as a defense mechanism. Once sprayed onto a victim's skin, the venom acts as a severe irritant. If it is introduced to the eye, it can cause a severe burning sensation and temporary or even permanent blindness if not cleaned out immediately and thoroughly.

Contrary to popular belief, the Philippine cobra (N. philippinensis) is not the most venomous Naja species. The Caspian cobra (N. oxiana) of Central Asia produces a more toxic venom. The average subcutaneous LD50 for N. oxiana in mice is 0.18 mg/kg, and the lowest reported value for N. oxiana is 0.10 mg/kg SC.[6] while N. philippinensis has an average murine LD50 of 0.2 mg/kg SC.[7] The lowest value reported for N. philippinensis is 0.14 mg/kg SC.[8] In mice, the IV LD50 for the Caspian cobra it's 0.037 mg/kg,[9] and for the Philippine cobra it's 0.05 mg/kg.[10] The Caspian cobra is the most venomous species of cobra in the world. The crude venom of N. oxiana produced the lowest known lethal dose (LCLo) of 0.005 mg/kg, the lowest among all cobra species ever recorded, derived from an individual case of poisoning by intracerebroventricular injection.[11] After the Caspian cobra and the Philippine cobra, is the Forest cobra with a LD50 of 0.225 mg/kg SC,[9][12] followed by the Samar cobra (N. samarensis) which has a value of 0.23 mg/kg SC.[12] The water cobras of central Africa are also highly venomous. The murine intraperitoneal LD50 of Naja annulata and Naja christyi venoms were 0.143 mg/kg and 0.120 mg/kg, respectively.

The Naja species are a medically important group of snakes due to the number of bites and fatalities they cause across their geographical range. They range throughout Africa (including some parts of the Sahara where Naja haje can be found), Southwest Asia, Central Asia, South Asia, East Asia, and Southeast Asia. But unlike some other members of the Elapidae family (the species of the genus Bungarus, genus Oxyuranus, genus Pseudohaje, and especially genus Dendroaspis), the majority of bites by both African and Asian species of the genus Naja are "dry bites" (a dry bite is a bite by venomous snake which does not inject venom). Roughly 45-50% (sometimes more) of bites by most cobra species are dry bites and thus don't cause envenomation.[13] Some of the species which are well known and documented to not envenomate in a bite include: Naja naja, Naja kaouthia, Naja sputatrix, Naja siamensis, Naja haje, Naja annulifera, Naja anchietae and Naja nigricollis. Some species will inject venom in many of their bites, but still have a high number of bites which don't envenomate and some of those species include: Naja sumatrana, Naja melanoleuca, Naja atra, Naja mossambica and Naja katiensis. Among the genus, there are a few species in which "dry bites" are very rare. Envenoming occurs in more than 80% of bite cases among bites by these species. The species which typically inject venom in almost all their bites include some of the more dangerous and venomous species of this genus: Naja oxiana, Naja philippinensis, Naja nivea, and Naja samarensis. There are many more species within the genus which have not yet been subject to much research and studies, and as a result, very little is known about their behaviour, venom, diet, habitat and general temperaments. Some of these species include Naja sagittifera, Naja annulata, Naja christyi and many others.

There are many factors which influence the differences in cases of fatality among different species within the same genus. Among cobras, the cases of fatal outcome of bites in both treated and untreated victims can be quite vast. For example, mortality rates among untreated cases of envenomation by the cobras as a whole group ranges from 6.5-20% for Naja naja[14] to about 80% for Naja oxiana.[15] Mortality rate for Naja atra is between 15-20%,[14] 5-10% for Naja nigricollis,[16] 50% for Naja nivea,[14] 65-70% for Naja melanoleuca, 7-13% for Naja kaouthia,[17] and 55-60% for Naja samarensis.[18] In cases where victims of cobra bites that are medically treated using normal treatment protocol for elapid type envenomation also show differences in prognosis depending on the cobra species involved. The vast majority of envenomated patients treated make quick and complete recovery, while other envenomated patients who receive similar treatment result in fatality. The most important factors in the difference of mortality rates among victims envenomated by cobras is the severity of the bite and which cobra species caused the envenomation. Species like the Caspian cobra (N. oxiana) and the Philippine cobra (N. philippinensis) are the two cobra species with the most toxic venoms based on LD50 studies on mice. Both species cause prominent neurotoxicity and progression of life-threatening symptoms following envenomation by either species is rapid. Death has been reported in as little as 30 minutes in cases of envenomation by both species. N. philippinensis has a purely neurotoxic venom that causes prominent neurotoxicity with minimal local tissue damage and pain[19] and patients respond very well to antivenom therapy if treatment is administered rapidly post-envenomation. Envenomation caused by N. oxiana is much more complicated. In addition to prominent neurotoxicity, there are very potent cytotoxic and cardiotoxic components in the species' venom. Local effects are marked and manifest in all cases of envenomation. There's severe pain, severe swelling, bruising, blistering, and tissue necrosis. Renal damage and cardiotoxicity are also clinical manifestations of envenomation causedu by N. oxiana, though they are rare and secondary.[20] The untreated mortality rate among those envenomed by Naja oxiana approach 80%, the highest among all species within the genus Naja.[15] Antivenom is not as effective for envenomation by this species as it is for other Asiatic cobras within the same region, like the Indian cobra (Naja naja) and due to the dangerous toxicity of this species' venom, massive amounts of antivenom are often required for patients. As a result, a monovalent antivenom serum is being developed by the Razi Vaccine and Serum Research Institute in Iran. Response to treatment with antivenom is generally poor among patients, so mechanical ventilation and endotracheal intubation is required. As a result, mortality among those treated for N. oxiana envenomation is still relatively high (up to 30%) compared to all other species of cobra (<1%).[21]

Species[edit]

Species[1] Authority[1] Subsp.*[1] Common name Geographic range
N. anchietae Bocage, 1879 0 Anchieta's cobra (Angolan Cobra) Angola, Botswana, Namibia, Zambia, eastern Zimbabwe
N. annulata (Buchholz and Peters, 1876) 1 Banded water cobra Cameroon, Central African Republic, Democratic Republic of Congo, Republic of Congo, Equatorial Guinea, Gabon, Rwanda, and the province of Cabinda in Angola
N. annulifera Peters, 1854 0 Snouted cobra Botswana, Malawi, Mozambique, South Africa, Swaziland, Zambia, Zimbabwe
N. arabica Scortecci, 1932 0 Arabian cobra Oman, Saudi Arabia, Yemen
N. ashei Wüster and Broadley, 2007 0 Ashe's spitting cobra (giant spitting cobra) Southern Ethiopia, Kenya, Somalia, eastern Uganda
N. atra Cantor, 1842 0 Chinese cobra Southern China, northern Laos, Taiwan, northern Vietnam
N. christyi (Boulenger, 1904) 0 Congo water cobra Democratic Republic of Congo, Republic of Congo, and in the province of Cabinda in Angola
N. haje (Linnaeus, 1758) Egyptian cobra Algeria, Burkina Faso, Cameroon, Central African Republic, northern Democratic Republic of the Congo, Chad, Egypt, Eritrea, Ethiopia, Kenya, Libya, Mali, Mauritania, Morocco, Niger, Nigeria, Somalia, Sudan, Tanzania, Togo, Tunisia, Uganda, Western Sahara
N. kaouthia Lesson, 1831 0 Monocled cobra Bangladesh, Bhutan, Burma, Cambodia, southern China, eastern India, Laos, northwestern Malaysia, Nepal, Thailand, southeastern Tibet, Vietnam
N. katiensis Angel, 1922 0 Mali cobra Benin, Burkina Faso, Cameroon, Ghana, Guinea, Ivory Coast, Mali, Gambia, Mauritania, Niger, Nigeria, Senegal, Togo
N. mandalayensis Slowinski & Wüster, 2000 0 Mandalay spitting cobra (Burmese spitting cobra) Burma
N. melanoleuca Hallowell, 1857 0 Forest cobra Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo (Zaire), Congo, Ethiopia, Gabon, Ghana, Gambia, Guinea, Guinea Bissau, Ivory Coast, Kenya, Liberia, Malawi, Mali, Mozambique, Niger, Nigeria, Rwanda, Sao Tom'e, Senegal, Sierra Leone, Somalia, South Africa, Sudan, Tanzania, Togo, Uganda, Zambia, Zimbabwe
N. mossambica Peters, 1854 0 Mozambique spitting cobra Extreme southeastern Angola, Botswana, Malawi, Mozambique, Somalia, northeastern Namibia, South Africa, Swaziland, Tanzania (including Pemba Island), Zambia, Zimbabwe
N. multifasciata Werner, 1902 0 Burrowing cobra Cameroon, Congo, Democratic Republic of the Congo (Zaire), Gabon
N. naja (Linnaeus, 1758) 0 Indian cobra (spectacled cobra) Bangladesh, Bhutan, India, Nepal, Pakistan, Sri Lanka
N. nigricincta Bogert, 1940 1 Zebra spitting cobra Angola, Namibia, South Africa
N. nigricollis Reinhardt, 1843 0 Black-necked spitting cobra Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Democratic Republic of the Congo (except in the center), Congo, Ethiopia, Gabon, Gambia, Ghana, Guinea Bissau, Guinea, Ivory Coast, Kenya, Liberia, Mali, Mauritania, Namibia, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Sudan, Tanzania, Somalia, Togo, Uganda, Zambia
N. nivea (Linnaeus, 1758) 0 Cape cobra (yellow cobra) Botswana, Lesotho, Namibia, South Africa
N. nubiae Wüster & Broadley, 2003 0 Nubian spitting cobra Chad, Egypt, Eritrea, Niger, Sudan
N. oxiana (Eichwald, 1831) 0 Caspian cobra Afghanistan, northwest India, Iran, Kyrgyzstan, Pakistan, Tajikistan, Turkmenistan, Uzbekistan
N. pallida Boulenger, 1896 0 Red spitting cobra Djibouti, Ethiopia, Kenya, Somalia, Tanzania
N. philippinensis Taylor, 1922 0 Philippine cobra Philippines (Luzon, Mindoro)
N. romani Hofstetter, 1939 0 European cobra Europe
N. sagittifera Wall, 1913 0 Andaman cobra India (Andaman Islands)
N. samarensis Peters, 1861 0 Peters' cobra Philippines (Mindanao, Bohol, Leyte, Samar, Camiguin)
N. senegalensis Trape, Chirio & Wüster, 2009 0 Senegalese cobra Benin, Burkina Faso, Ghana, Guinea, Mali, Niger, Nigeria, Senegal
N. siamensis Laurenti, 1768 0 Indo-Chinese spitting cobra Cambodia, Laos, Thailand, Vietnam
N. sputatrix F. Boie, 1827 0 Javan spitting cobra Indonesia (Java, Lesser Sunda Islands, East Timor)
N. sumatrana Müller, 1887 0 Equatorial spitting cobra Brunei, Indonesia (Sumatra, Borneo, Bangka, Belitung), Malaysia, Philippines (Palawan), southern Thailand, Singapore

* Not including the nominate subspecies.
Extinct.
T Type species.[22]

Taxonomy[edit]

The genus contains several species complexes of closely related and often similar species, some of them only recently described or defined. Several recent taxonomic studies have revealed species not included in the current listing in ITIS:[1]

  • Naja anchietae (Bocage, 1879), or Anchieta's cobra, is regarded as a subspecies of N. haje by Mertens (1937) and of N. annulifera by Broadley (1995). It is regarded as a full species by Broadley and Wüster (2004).[23][24]
  • Naja arabica Scortecci, 1932, the Arabian cobra, has long been considered a subspecies of N. haje, but was recently raised to the status of species.[25]
  • Naja ashei Broadley and Wüster, 2007, Ashe's spitting cobra, is a newly described species found in Africa.[26][27]
  • Naja nigricincta Bogert, 1940, was long regarded as a subspecies of N. nigricollis, but was recently found to be a full species (with N. n. woodi as a subspecies).[28][29]
  • Naja senegalensis Trape et al., 2009, is a new species encompassing what were previously considered to be the West African savanna populations of N. haje.[25]

Two recent molecular phylogenetic studies have also supported the incorporation of the species normally assigned to the genera Boulengerina and Paranaja into Naja, as both are closely related to the forest cobra (Naja melanoleuca).[28][30]

Wallach et al.[2] suggested recognition of four subgenera within Naja: Naja for the Asiatic cobras, Boulengerina for the African forest, water and burrowing cobras, Uraeus for the Egyptian and Cape cobra group and Afronaja for the African spitting cobras.

References[edit]

  1. ^ a b c d e "Naja". Integrated Taxonomic Information System. Retrieved 13 April 2008. 
  2. ^ a b Wallach, Van; Wüster, W; Broadley, Donald G. (2009). "In praise of subgenera: taxonomic status of cobras of the genus Naja Laurenti (Serpentes: Elapidae)". Zootaxa 2236 (1): 26–36. 
  3. ^ "Proto-IE: *(s)nēg-o-, Meaning: snake, Old Indian: nāgá- m. 'snake', Germanic: *snēk-a- m., *snak-an- m., *snak-ō f.; *snak-a- vb". Starling.rinet.ru. 
  4. ^ Mayrhofer, Manfred (1996). Etymologisches Wörterbuch des Altindoarischen. Heidelberg: Universitätsverlag C. Winter. p. II.33. ISBN 3-8253-4550-5. 
  5. ^ "Naja melanoleuca - General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid, Antivenoms". WCH Clinical Toxinology Resource. University of Queensland. Retrieved 17 December 2011. 
  6. ^ Khare, AD; Khole V; Gade PR (December 1992). "Toxicities, LD50 prediction and in vivo neutralisation of some elapid and viperid venoms". Indian Journal of Experimental Biology 30 (12): 1158–62. PMID 1294479. Retrieved 6 December 2013. 
  7. ^ Brown, John H. (1973). Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, IL US: Charles C. Thomas. p. 81. ISBN 0-398-02808-7. 
  8. ^ Watt, G; Theakston RD; Hayes CG; Yambao ML; Sangalang R; et al. (4 December 1986). "Positive response to edrophonium in patients with neurotoxic envenoming by cobras (Naja naja philippinensis). A placebo-controlled study". New England Journal of Medicine 315 (23): 1444–8. doi:10.1056/NEJM198612043152303. PMID 3537783. Retrieved 6 December 2013. 
  9. ^ a b Zug, George R. (1996). Snakes in Question: The Smithsonian Answer Book. Washington D.C., US: Smithsonian Institution Scholarly Press. ISBN 1-56098-648-4. 
  10. ^ Hauert, Jacques; ichel Maire; Alexandre Sussmann; Dr. J. Pierre Bargetz (July 1974). "THE MAJOR LETHAL NEUROTOXIN OF THE VENOM OF NAJA NAJA PHILIPPINENSIS: Purification, physical and chemical properties, partial amino acid sequence". International Journal of Peptide and Protein Research 6 (4): 201–222. doi:10.1111/j.1399-3011.1974.tb02380.x. Retrieved 6 December 2013. 
  11. ^ Lysz, Thomas W.; Rosenberg, Philip (May 1974). "Convulsant activity of Naja naja oxiana venom and its phospholipase A component". Toxicon 12 (3): 253–265. doi:10.1016/0041-0101(74)90067-1. 
  12. ^ a b Minton, SA (1967). "Paraspecific protection by elapid and sea snake antivenins". Toxicon 5 (1): 47–55. doi:10.1016/0041-0101(67)90118-3. 
  13. ^ Warrell, DA; Theakston RD; Griffiths E (April 2003). "Report of a WHO workshop on the standardization and control of antivenoms". Toxicon 41 (5): 541–57. doi:10.1016/S0041-0101(02)00393-8. PMID 12676433. Retrieved 8 December 2013. 
  14. ^ a b c Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.
  15. ^ a b Gopalkrishnakone, Chou, P., LM (1990). Snakes of Medical Importance (Asia-Pacific Region). Singapore: National University of Singapore. ISBN 9971-62-217-3. [page needed]
  16. ^ Warrell, David A. "Snake bite". Seminar. Lancet 2010 (volume 375, issue 1). Retrieved 20 December 2011. 
  17. ^ Norris MD, Robert L.; Minton, Sherman A. (10 September 2013). "Cobra Envenomation". Medscape. United States: Medscape. Retrieved 8 December 2013. 
  18. ^ Solevilla, Rosalinda C (1997). "A preliminary study of the toxic principles from the venom of Naja naja samarensis, Peters". Acta Manilana 40 (0): 1–6. 
  19. ^ Watt, G.; Padre L; Tuazon L; Theakston RD; Laughlin L. (September 1988). "Bites by the Philippine cobra (Naja naja philippinensis): prominent neurotoxicity with minimal local signs". The American Journal of Tropical Medicine and Hygiene 39 (3): 306–11. PMID 3177741. Retrieved 8 December 2013. 
  20. ^ "Naja oxiana". Clinical Toxinology Resource. University of Adelaide. Retrieved 8 December 2013. 
  21. ^ Latifi, Mahmoud (1984). Snakes of Iran. Society for the Study of Amphibians & Reptiles. ISBN 978-0-916984-22-9. 
  22. ^ Zhao E, Adler K. 1993. Herpetology of China. Society for the Study of Amphibians and Reptiles. 522 pp. LCCN 92-61941. ISBN 0-916984-28-1.
  23. ^ Broadley, D.G. & W. Wüster (2004) A review of the southern African 'non-spitting' cobras (Serpentes: Elapidae: Naja). African Journal of Herpetology 53:101-122.
  24. ^ Naja anchietae at the Reptarium.cz Reptile Database. Accessed 13 April 2007.
  25. ^ a b Trape, J.-F., L. Chirio, D.G. Broadley & W. Wüster (2009) Phylogeography and systematic revision of the Egyptian cobra (Serpentes: Elapidae: Naja haje) species complex, with the description of a new species from West Africa. Zootaxa 2236: 1-25.
  26. ^ Wüster, W. & D.G. Broadley (2007) Get an eyeful of this: a new species of giant spitting cobra from eastern and north-eastern Africa (Squamata: Serpentes: Elapidae: Naja). Zootaxa 1532: 51-68
  27. ^ Naja ashei at the Reptarium.cz Reptile Database. Accessed 13 April 2007.
  28. ^ a b Wüster, W., S. Crookes, I. Ineich, Y. Mane, C.E. Pook, J.-F. Trape & D.G.Broadley (2007) The phylogeny of cobras inferred from mitochondrial DNA sequences: evolution of venom spitting and the phylogeography of the African spitting cobras (Serpentes: Elapidae: Naja nigricollis complex). Molecular Phylogenetics and Evolution, 45: 437-453.
  29. ^ Naja nigricincta at the Reptarium.cz Reptile Database. Accessed 29 December 2008.
  30. ^ Nagy, Z.T., Vidal, N., Vences, M., Branch, W.R., Pauwels, O.S.G., Wink, M., Joger, U., 2005. Molecular systematics of African Colubroidea (Squamata: Serpentes). In: Huber, B.A., Sinclair, B.J., Lampe, K.-H. (Eds.), African Biodiversity: Molecules, Organisms, Ecosystems. Museum Koenig, Bonn, pp. 221–228.

External links[edit]