Venomous Snakes

Venomous snake
From Wikipedia, the free encyclopedia

"Poisonous snake" redirects here. For true poisonous snakes, see Rhabdophis.

The Indian Cobra (Naja naja), one of the most well-known venomous snakes.

Venomous snakes are snakes which have venom glands and specialized teeth for the injection of venom. Members of the families Elapidae, Viperidae, Hydrophiidae, and Atractaspididae (and some from Colubridae as well) are major venomous snakes.Contents [hide]
1 Description
2 Most venomous snake
3 Other information
4 Families of venomous snakes
5 See also
6 References
7 External links

[edit]
Description

Venomous snakes use modified saliva, snake venom, usually delivered through highly specialized teeth such as hollow fangs, for the purpose of prey immobilization and self-defense. In contrast, non-venomous species either constrict their prey, or simply overpower it with their jaws.

Venomous snakes include several families of snakes and do not form a single taxonomic group. This has been interpreted to mean that venom in snakes originated more than once as the result of convergent evolution. Evidence has recently been presented for the Toxicofera hypothesis however; venom was present (in small amounts) in the ancestor of all snakes (as well as several lizard families) as 'toxic saliva' and evolved to extremes in those snake families normally classified as venomous by parallel evolution. The Toxicofera hypothesis further implies that 'non venomous' snake lineages have either lost the ability to produce venom (but may still have lingering venom pseudogenes), or actually do produce venom in small quantities, likely sufficient to assist in small prey capture, but cause no harm to humans if bitten.
[edit]
Most venomous snake

Lists or rankings of the world's "most venomous snakes" are tentative and differ greatly due to numerous factors, including the recentness and reliability of the data, the number of species analyzed, and the testing methods used.[1] In addition, since mice are the common indicator used to test venom from venomous snakes in LD50 test, the LD50 results may not reflect the actual effects on humans due to the physiological differences between mice and humans. For example, many venomous snakes are specialized predators on mice, and their venom may be adapted specifically to incapacitate mice. While most mammals have a very similar physiology, LD50 results may or may not be directly relevant to humans.

Moreover, in terms of many other factors, the most venomous species may not always be the most dangerous; for example, while the Russell's viper, the Saw-scaled viper, the King cobra and the Black mamba are regarded to have weaker venom than the Inland taipan, the prior two are responsible for far more deaths due to various factors (such as their wide distributions and inconspicuous appearance), while the latter two cause higher mortality rates and a faster death time in humans due to their high attack position and large dose of highly potent venom delivered.[2]

While there have been numerous studies on snake venom, potency estimates can vary,[3] creating overlap and greatly complicating the task. Further, LD50 may be measured through intramuscular, intraperitoneal, intravenous or subcutaneous injections on small rodents, although the latter is the most applicable to actual bites.[1] It should also be considered that mice, the most commonly used animals in determining LD50, may react to some snake venoms differently than humans do.[4] Thus, it remains difficult to compile such lists.

Many of these lists only take into account of terrestrial and arboreal snakes and neglect to list the of venom of the sea snakes. Species of sea snakes have been listed to have more toxic venom than even that of the inland taipan and further investigations of some species' venom are needed.
[edit]
Other information

Venomous snakes are often said to be poisonous, although this is not the correct term, as venoms and poisons are different. Poisons can be absorbed by the body, such as through the skin or digestive system, while venoms must first be introduced directly into tissues or the blood stream (envenomated) through mechanical means. It is, for example, therefore harmless to drink snake venom as long as there are no lacerations inside the mouth or digestive tract. There are however two exceptions: the Rhabdophis snakes (keelback snakes) secrete poison from glands that it gets from the poisonous toads that it preys on; similarly certain garter snakes from Oregon retain toxins in their liver from the newts they eat.[5]
[edit]
Families of venomous snakes

Over 600 species are known to be venomous—about a quarter of all snake species. The following table lists some major species.Family Description
Atractaspididae (atractaspidids) Burrowing asps, mole vipers, stiletto snakes.
Colubridae (colubrids) Most are harmless, but others have toxic saliva and at least five species, including the boomslang (Dispholidus typus), have caused human fatalities.
Elapidae (elapids) Sea snakes, Taipans, Brown snakes, Coral snakes, Kraits, King Cobra, Mambas, Cobras.
Viperidae (viperids) True vipers and pit vipers, including rattlesnakes and copperheads and cottonmouths.

[edit]
See also
Snakebite
Snake venom
Big Four (Indian snakes)
List of venomous animals
venomous fish
Venomous mammals
Poisonous Amphibians
Toxic Birds
[edit]
References
^ a b Fry, Bryan Grieg. "Snake LD50 - discussion". Australian Venom & Toxin Database. Retrieved 2009-09-28. "Subcutaneous is the most applicable to actual bites. Only large Bitis or extremely large Bothrops or Crotalus specimens wouls be able to deliver a bite that is truly intramuscular. IV injections are extremly rare in actual bites."
^ Chippaux, J.P. (1998). "Snake-bites: appraisal of the global situation". Bulletin of the World Health Organization 76 (5): 515–24. PMC 2305789. PMID 9868843. Retrieved 2009-07-03.
^ Mackessy, Stephen P. (June 2002). "Biochemistry and pharmacology of colubrid snake venoms". Journal of Toxicology: Toxin Reviews 21 (1–2): 43–83. doi:10.1081/TXR-120004741. Retrieved 2009-09-26.
^ "Venom variability". Women's & Children's Hospital - Clinical Toxinology Resources. University of Adelaide. Retrieved 28 September 2009. "The rough scaled snake, Tropidechis carinatus has a much less potent venom than the tiger snake, Notechis scutatus, on LD50 testing in mice. Yet clinically, the two venoms are virtually identical in the type and severity of effects on envenomed humans."
^ Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. University of California Press, Berkeley. ISBN 0-520-21056-5.
[edit]
External links
Venomous Snake Community Pictures, forums, Classifieds and Venomous snake species listings
For goodness snakes Treating and Preventing Venomous Bites.
Venomous snakes and outdoor workers Bite-prevention and treatment information for outdoor workers.
View page ratings
Rate this page
What's this?
Trustworthy
Objective
Complete
Well-written
I am highly knowledgeable about this topic (optional