Naja: Difference between revisions
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Several ''Naja'' species, referred to as [[spitting cobra]]s, have developed a specialized venom delivery mechanism, in which their [[proteroglypha|front fangs]], instead of releasing venom through the tips (similar to a [[hypodermic needle]]), have a [[rifling|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. | Several ''Naja'' species, referred to as [[spitting cobra]]s, have developed a specialized venom delivery mechanism, in which their [[proteroglypha|front fangs]], instead of releasing venom through the tips (similar to a [[hypodermic needle]]), have a [[rifling|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. | ||
Murine [[Subcutis|Subcutaneous]] LD<sub>50</sub> values for some cobra species include 0.20 mg/kg for ''Naja philippinensis'' ([[Philippine cobra]]) which is considered to be the most venomous species, 0.40 mg/kg for ''Naja oxiana'' ([[ | Murine [[Subcutis|Subcutaneous]] LD<sub>50</sub> values for some cobra species include 0.20 mg/kg for ''Naja philippinensis'' ([[Philippine cobra]]) which is considered to be the most venomous species, 0.40 mg/kg for ''Naja oxiana'' ([[Central Asian cobra]]), 0.80 mg/kg for ''Naja naja'' ([[Indian cobra]]),<ref name=Brown>{{cite book|last=Brown Ph.D|first=John H.|title=Toxicology and Pharmacology of Venoms from Poisonous Snakes|year=1973|publisher=Charles C. Thomas Publishers|location=Springfield, IL USA|isbn=0-398-02808-7|pages=81–82}}</ref> 1.15 mg/kg for ''Naja haje'' ([[Egyptian cobra]]), 2.0 mg/kg for ''Naja nigricollis'' ([[Naja nigricollis|Black-necked spitting cobra]]), 0.72 mg/kg for ''Naja nivea'' ([[Cape cobra]]),<ref name=VenDoc>{{cite web|last=Fry|first=Bryan Grieg|title=LD50|url=http://www.venomdoc.com/LD50/ld50sc.html|work=Australian Venom Research Unit|publisher=University of Queensland|accessdate=7 May 2012}}</ref> and 0.53 mg/kg for ''Naja atra'' ([[Naja atra|Chinese cobra]]).<ref name=SI>{{cite book|title=Snakes of medical importance|publisher=Venom and toxic research group|location=Singapore|isbn=9971-62-217-3|pages=253|url=http://i55.tinypic.com/21jvc7p.jpg}}</ref> | ||
Some murine [[Intravenous therapy|IV]] LD<sub>50</sub> values include 0.29 mg/kg for ''Naja melanoleuca'' ([[Forest cobra]]), 0.345 mg/kg for ''Naja atra'' (Chinese cobra), 0.373 mg/kg for ''Naja kaouthia'' ([[Monocled cobra]]), and 0.96 mg/kg for ''Naja oxiana'' ([[ | Some murine [[Intravenous therapy|IV]] LD<sub>50</sub> values include 0.29 mg/kg for ''Naja melanoleuca'' ([[Forest cobra]]), 0.345 mg/kg for ''Naja atra'' (Chinese cobra), 0.373 mg/kg for ''Naja kaouthia'' ([[Monocled cobra]]), and 0.96 mg/kg for ''Naja oxiana'' ([[Central Asian cobra]]).<ref name=VenDoc/> | ||
The murine [[Intraperitoneal injection|IP]] LD<sub>50</sub> of ''Naja annulata'' ([[Banded water cobra]]) and ''Naja christyi'' ([[Congo water cobra]]) venoms were 0.143 and 0.120 mg/kg, respectively.<ref name=Toxicon>{{cite journal|last=Weinstein|first=Scott A.|coauthors=James J. Schmidt, Leonard A. Smith|title=Lethal toxins and cross-neutralization of venoms from the African water cobras, Boulengerina annulata annulata and Boulengerina christyi.|journal=Toxicon|date=30|year=1991|month=March|volume=29|issue=11|pages=1315–1327|pmid=1814007|url=http://www.ncbi.nlm.nih.gov/pubmed/1814007|accessdate=7 May 2012}}</ref> Other [[Intraperitoneal injection|IP]] LD<sub>50</sub> values include ''Naja haje'' (Egyptian cobra) at 0.185 mg/kg, for ''Naja kaouthia'' (Monocled cobra) it's 0.225 mg/kg, for ''Naja naja'' (Indian cobra) it's 0.315 mg/kg, for ''Naja melanoleuca'' (Forest cobra) it's 0.324 mg/kg, for ''Naja nivea'' (Cape cobra) it's 0.4 mg/kg, for ''Naja nigricollis'' (Black-necked spitting cobra) it's 0.4 mg/kg, and for ''Naja pallida'' ([[Red spitting cobra]]) it's 2.0 mg/kg.<ref name=VenDoc/> | The murine [[Intraperitoneal injection|IP]] LD<sub>50</sub> of ''Naja annulata'' ([[Banded water cobra]]) and ''Naja christyi'' ([[Congo water cobra]]) venoms were 0.143 and 0.120 mg/kg, respectively.<ref name=Toxicon>{{cite journal|last=Weinstein|first=Scott A.|coauthors=James J. Schmidt, Leonard A. Smith|title=Lethal toxins and cross-neutralization of venoms from the African water cobras, Boulengerina annulata annulata and Boulengerina christyi.|journal=Toxicon|date=30|year=1991|month=March|volume=29|issue=11|pages=1315–1327|pmid=1814007|url=http://www.ncbi.nlm.nih.gov/pubmed/1814007|accessdate=7 May 2012}}</ref> Other [[Intraperitoneal injection|IP]] LD<sub>50</sub> values include ''Naja haje'' (Egyptian cobra) at 0.185 mg/kg, for ''Naja kaouthia'' (Monocled cobra) it's 0.225 mg/kg, for ''Naja naja'' (Indian cobra) it's 0.315 mg/kg, for ''Naja melanoleuca'' (Forest cobra) it's 0.324 mg/kg, for ''Naja nivea'' (Cape cobra) it's 0.4 mg/kg, for ''Naja nigricollis'' (Black-necked spitting cobra) it's 0.4 mg/kg, and for ''Naja pallida'' ([[Red spitting cobra]]) it's 2.0 mg/kg.<ref name=VenDoc/> | ||
Revision as of 11:28, 11 May 2012
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 A forest cobra
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Naja is a genus of venomous snakes belonging to the Elapidae family and ranging from Africa to the Middle East, Central Asia, South Asia (Indian subcontinent), Southeast Asia, and far East Asia. Although there are several other genera that share the common name, Naja are the most recognized and most widespread group of snakes commonly known as cobras. The genus Naja consists of 20 to 23 species, but has undergone several taxonomic revisions in recent years, so sources vary greatly.[1]
Etymology
The generic name naja is a Latinisation of the Sanskrit word nāgá (नाग) meaning "cobra" or snake.
Description
Different Naja species range in length and most are relatively slender-bodied snakes. Most species are capable of attaining lengths of 1.84 m (6.04 ft). Maximum lengths for some of the larger species of cobra is around 3.1 m (10.17 ft), with the Forest cobra being the longest species.[2][3] All have a characteristic ability to raise the front quarters of their bodies off the ground and flatten their necks to form a hood to appear larger to a potential predator.
Venom
All species in the genus Naja are capable of delivering a fatal bite in 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 developed 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.
Murine Subcutaneous LD50 values for some cobra species include 0.20 mg/kg for Naja philippinensis (Philippine cobra) which is considered to be the most venomous species, 0.40 mg/kg for Naja oxiana (Central Asian cobra), 0.80 mg/kg for Naja naja (Indian cobra),[4] 1.15 mg/kg for Naja haje (Egyptian cobra), 2.0 mg/kg for Naja nigricollis (Black-necked spitting cobra), 0.72 mg/kg for Naja nivea (Cape cobra),[5] and 0.53 mg/kg for Naja atra (Chinese cobra).[6]
Some murine IV LD50 values include 0.29 mg/kg for Naja melanoleuca (Forest cobra), 0.345 mg/kg for Naja atra (Chinese cobra), 0.373 mg/kg for Naja kaouthia (Monocled cobra), and 0.96 mg/kg for Naja oxiana (Central Asian cobra).[5]
The murine IP LD50 of Naja annulata (Banded water cobra) and Naja christyi (Congo water cobra) venoms were 0.143 and 0.120 mg/kg, respectively.[7] Other IP LD50 values include Naja haje (Egyptian cobra) at 0.185 mg/kg, for Naja kaouthia (Monocled cobra) it's 0.225 mg/kg, for Naja naja (Indian cobra) it's 0.315 mg/kg, for Naja melanoleuca (Forest cobra) it's 0.324 mg/kg, for Naja nivea (Cape cobra) it's 0.4 mg/kg, for Naja nigricollis (Black-necked spitting cobra) it's 0.4 mg/kg, and for Naja pallida (Red spitting cobra) it's 2.0 mg/kg.[5]
Taxonomy
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). A.k.a. Anchieta's cobra. Regarded as a subspecies of N. haje by Mertens (1937) and of N. annulifera by Broadley (1995). Regarded as a full species by Broadley and Wüster (2004).[8]
- Naja arabica Scortecci, 1932. A.k.a. Arabian cobra. Long considered a subspecies of N. haje, this was recently raised to the status of a whole species [9]
- Naja ashei Broadley and Wüster, 2007. A.k.a. Ashe’s spitting cobra. This is a newly described species found in Africa.[10]
- Naja nigricincta Bogert, 1940. This was long regarded as a subspecies of Naja nigricollis, but was recently found to be a full species (with N. nigricincta woodi as a subspecies).[11]
- Naja senegalensis Trape et al., 2009. This new species, encompassing what were previously considered to be the West African savanna populations of N. haje, was recently described as a new species.[9]
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) [11][12]
Species
| Species[1] | Authority[1] | Subsp.*[1] | Common name | Geographic range |
|---|---|---|---|---|
| N. anchietae | Bocage, 1879 | 0 | Anchieta's 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 & 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 SE Angola, Botswana, Malawi, Mozambique, Somalia, NE Namibia, South Africa, Swaziland, Tanzania (including Pemba Island), Zambia, Zimbabwe |
| N. najaT | (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 & Broadly, 2003 | 0 | Nubian spitting cobra | Chad, Egypt, Eritrea, Niger, Sudan |
| N. oxiana | (Eichwald, 1831) | 0 | Caspian cobra | Afghanistan, North-west 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. 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, ?Guinea-Bissau, ?Ivory Coast, 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.
T) Type species.[13]
Cited references
- ↑ 1.0 1.1 1.2 1.3 1.4 Naja (TSN 700233) at Integrated Taxonomic Information System. Accessed 7 May 2012.
- ↑ Naja melanoleuca - General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid, Antivenoms. WCH Clinical Toxinology Resource. University of Queensland. Retrieved on 7 May 2012.
- ↑ Burton, Maurice. (2002). International Wildlife Encyclopedia. United States: Marshall Cavendish Corp; 3rd edition. pp. 481-482. ISBN 0761472703.
- ↑ Brown Ph.D, John H. (1973). Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, IL USA: Charles C. Thomas Publishers, 81–82. ISBN 0-398-02808-7.
- ↑ 5.0 5.1 5.2 Fry, Bryan Grieg. LD50. Australian Venom Research Unit. University of Queensland. Retrieved on 7 May 2012.
- ↑ Snakes of medical importance. Singapore: Venom and toxic research group, 253. ISBN 9971-62-217-3.
- ↑ Weinstein, Scott A.; James J. Schmidt, Leonard A. Smith (30). "Lethal toxins and cross-neutralization of venoms from the African water cobras, Boulengerina annulata annulata and Boulengerina christyi.". Toxicon 29 (11): 1315–1327. PMID 1814007. Retrieved on 7 May 2012.
- ↑ 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.
- ↑ 9.0 9.1 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.
- ↑ 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
- ↑ 11.0 11.1 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.
- ↑ 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.
- ↑ Zhao E, Adler K. 1993. Herpetology of China. Society for the Study of Amphibians and Reptiles. 522 pp. LCCN 92-61941. ISBN 0-916984.
