Echis

Taxobox
name = "Echis"


image_caption = Saw-scaled viper, "E. carinatus"
regnum = Animalia
phylum = Chordata
subphylum = Vertebrata
classis = Reptilia
ordo = Squamata
subordo = Serpentes
familia = Viperidae
subfamilia = Viperinae
genus = "Echis"
genus_authority = Merrem, 1820
synonyms = * "Echis" - Merrem, 1820
* "Toxicoa" - Gray, 1849
* "Turanechis" - Cherlin, 1990McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).] :"Common names: saw-scaled vipers, carpet vipers.Spawls S, Branch B. 1995. The Dangerous Snakes of Africa. Ralph Curtis Books. Dubai: Oriental Press. 192 pp. ISBN 0-88359-029-8.] ""Echis" is a genus of venomous vipers found in the dry regions of Africa, the Middle East, India and Sri Lanka. These snakes are quick-tempered and strike readily, which, combined with a virulent hemotoxic venom, makes them very dangerous, despite their small size. They also have a characteristic threat display, rubbing sections of their body together to produce a "sizzling" warning sound.Mallow D, Ludwig D, Nilson G. 2003. True Vipers: Natural History and Toxinology of Old World Vipers. Krieger Publishing Company, Malabar, Florida. 359 pp. ISBN 0-89464-877-2.] The name "Echis" is a Greek word that means "viper." [http://www.calflora.net/botanicalnames/pageE.html E] at [http://www.calflora.net/botanicalnames/index.html California Plant Names: Latin and Greek Meanings and Derivations. A Dictionary of Botanical Etymology] . Accessed 26 January 2007.] Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.] Eight species are currently recognized.ITIS|ID=634423|taxon="Echis"|year=2006|date=31 July]

Description

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The head is short, wide, pear-shaped and distinct from the neck. The snout is short and rounded, while the eyes are relatively large and set well forward. The crown is covered with small, irregular, imbricate scales, which may be either smooth or keeled.

The body is moderately slender and cylindrical. The dorsal scales are mostly keeled. However, the scales on the lower flanks stick out at a distinct 45-degree angle and have a central ridge, or keel, that is serrated (hence the common name). The tail is short and the subcaudals single.

Geographic range

India and Sri Lanka, parts of the Middle East and Africa north of the equator.

Behavior

All members of this genus have a distinctive threat display, which involves forming a series of parallel C-shaped coils and rubbing them together to produce a sizzling sound, rather like water on a hot plate. The proper term for this is stridulation.Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.] As they become more agitated, this stridulating behavior becomes faster and louder. It is postulated that this display evolved as a means of limiting water loss, such as might occur when hissing. However, some authors describe this display as being accompanied by loud hissing.

These snakes are very aggressive and will strike vigorously from the position described above. When doing so, they may overbalance and end up moving towards their aggressor as a result; most unusual behavior for a snake.

Feeding

Little is known about the eating habits of some species, but of others the diet is reported to be extremely varied, and may include items such as locusts, beetles, worms, slugs, spiders, scorpions, centipedes, solifugids, frogs, toads, reptiles (including other snakes), small mammals and birds.

Reproduction

Most "Echis" species, such as those found in Africa, are oviparous, while others, such as those in India, are viviparous.

Venom

Bites from "Echis" species probably result in more deaths than from any other species. The genus is recognized as medically significant in many tropical rural areas. They may be small, but they are very aggressive, quick to strike and possess an extremely virulent hemotoxic venom. There seems to be no significant correlation between the length of the specimen and the symptomology signs that occur in humans. Most victims are bitten after dark when these snakes are active.

Most of these species have venom that contains factors that can cause a consumption coagulopathy and defibrination which may persist for days to weeks. This may result in bleeding anywhere in the body, including the possibility of an intracranial hemorrhage. The latter classically occurs a few days following the bite.Campbell CH. 1995. Snake bite and snake venoms: their effects on the nervous system. In: de Wolff FA, editor. Handbook of clinical neurology, vol 21 (65). Intoxications of the nervous system, part II. Amsterdam: Elsevier Science Publications.]

Venom toxicity varies among the different species, geographic locations, individual specimens, sexes, over the seasons, different milkings, and of course the method of injection (SC, IM, IP, IV). Consequently, the LD₅₀ values for "Echis" venom differ significantly. In mice the intravenous LD₅₀ ranges from 2.3 mg/kg (U.S. Navy, 1991), to 24.1 mg/kg (Christensen, 1955) to 0.44-0.48 mg/kg (Cloudsley-Thompson, 1988). In humans, the lethal dose is estimated to be 3-5 mg (Minton, 1967). Latifi (1991) notes that venom from females was more than twice as toxic on average than venom from males.

The amount of venom produced also varies. Reported yields include 20-35 mg of dried venom from specimens 41-56 cm in length (Minton 1974, U.S. Navy, 1991), 6-48 mg (16 mg average) from Iranian specimens (Latifi, 1991) and 13-35 mg of dried venom from animals from various other localities (Boquet, 1967). Yield varies seasonally, as well as between the sexes: the most venom is produced during the summer months and males produce more than females.

pecies

"*) Not including the nominate subspecies."
^T) Type species.

Taxonomy

Some sources also mention several other species:NRDB genus|genus=Echis|date=2 August|year=2007] [http://biology.bangor.ac.uk/~bss166/Updates/Viperinae2004.htm "Echis omanensis", Oman saw-scaled viper] at [http://biology.bangor.ac.uk/~bss166/ Wolfgang Wüster's homepage] . Accessed 7 June 2007.]

* "E. omanensis", Babocsay 2004. A new species found in the United Arab Emirates and east Oman.
* "E. khosatzkii", Cherlin 1990. Found in Oman and Yemen. Considered a synonym of "E. pyramidum".
* "E. multisquamatus", Cherlin 1981. Described here as "E. carinatus multisquamatus".

Trivia

*A saw scaled viper of the genus "Echis" may be responsible for biblical claims of a fiery flying serpent. [http://www.meridianmagazine.com/sci_rel/000609serpent.html What Fiery Flying Serpent Symbolized Christ?] at [http://www.meridianmagazine.com/ Meridian] . Accessed 22 June 2007.]

ee also

* List of viperine species and subspecies
*
*
* Snakebite

References

Further reading

* Boquet P. 1967. Pharmacology and toxicology of snake venoms of Europe and the Mediterranean regions. In: Bucherl W, editor. 1967. Venomous Animals and their Venoms. Vol. I. Paris: Masson. pp 340-58.
* Boulenger GA. 1890. The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. Taylor & Francis, London, xviii, 541 pp.
* Christensen PA. 1955. South African Snake Venoms and Antivenins. Johannesburg: South African Institute of Medical Research. 35 pp.
* Cloudsley-Thompson JL. 1988. The saw-scaled viper "Echis carinatus". British Herpetological Society Bulletin 24:32-3.
* Latifi M. 1991. The snakes of Iran. Published by the Department of the Environment and the Society for the Study of Amphibians and Reptiles, 2nd edition. 156 pp.
* Minton SA Jr. 1967. Snakebite. In: Beeson PB, McDermott W, editors. Cecil and Loeb Textbook of Medicine. Philadelphia: Saunders. 420 pp.
* Minton SA Jr. 1974. Venom Diseases. Springfield (IL): CC Thomas Publ. 386 pp.
* U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. ISBN 0-486-26629-X.

External links

* [http://www.herpbreeder.com/worldspecies/Snakes/vipers/echis.htm "Echis"] at [http://www.herpbreeder.com/ Herpbreeder.com] . Accessed 9 September 2006.
* [http://www.megasphera.cz/africanvenomoussnakes/_private/Fotogalerie_Efy.htm "Echis" photo gallery] at [http://www.megasphera.cz/africanvenomoussnakes/ Herpetology of Africa] . Accessed 9 September 2006.
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