Echis carinatus
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Common names: saw-scaled viper,[2] Indian saw-scaled viper, little Indian viper, [3] more.
Echis carinatus is a venomous viper species found in parts of the Middle East and Central Asia, and especially the Indian subcontinent. It is the smallest of the Big Four dangerous snakes of India.[4] Five subspecies are currently recognized, including the typical form described here.[5]
Description
Size ranges between 38 and 80 cm in length, but usually no more than 60 cm.[2]
Head distinct from neck, snout very short and rounded. The nostril between three shields and head covered with small keeled scales, among which an enlarged supraocular is sometimes present. There are 9-14 interocular scales across the top of the head and 14-21 circumorbital scales. 1-3 rows of scales separate the eye and the supralabials. There are 10-12 supralabials, the fourth usually largest, and 10-13 sublabials.[2][6]
Midbody there are 25-39 rows of dorsal scales that are keeled scales with apical pits; on the flanks, these have serrated keels. There are 143-189 ventral scales that are rounded and cover the full width of the belly. The subcaudals are undivided and number 21-52, and the anal scale is single.[2][6]
The color-pattern consists of a pale buff, grayish, reddish, olive or pale brown ground color, overlaid middorsally with a series of variably colored, but mostly whitish spots, edged with dark brown, and separated by lighter interblotch patches. A series of white bows run dorsolaterally. The top of the head has a whitish cruciform or trident pattern and there is a faint stripe running from the eye to the angle of the jaw. The belly is whitish to pinkish, uniform in color or with brown dots that are either faint or distinct.[2][6]
Common names
- English - saw-scaled viper,[2] Indian saw-scaled viper, little Indian viper.[3]
- Hindi - phoorsa.[7]
- Sinhala - vali polonga.[7]
- Tamil - surattai pambu.[7]
Geographic range
Asia. On the Indian subcontinent: India, Sri Lanka Bangladesh and Pakistan (including Urak near Quetta and Astola Island off the coast of Makran). In the Middle East: Oman, Masirah (Island), eastern United Arab Emirates and southwestern Iran. In Central Asia: Afghanistan, Uzbekistan, Turkmenistan and Tadzikhistan. The type locality was not included in the original description; given as "Arni" (India) by Russell (1796:3).[1]
Habitat
Found on a range of different substrates, including sand, rock, soft soil and in scrublands. Often found hiding under loose rocks. Specimens have also been found in Balochistan at altitudes of up to 1982 m.[2]
Behavior
This species is mostly crepuscular and nocturnal, although there have been reports of activity during daylight hours. [2] During they daytime they hide in all kinds of places, such as deep mammal burrows, rock fissures an fallen rotted logs. In sandy environments, they may bury themselves leaving only the head exposed. Often, they are most active after rains or on humid nights.[8]
When alarmed, they put on a distinctive threat display (see Echis).[2]
They move about mainly sidewinding: a method at which they are considerably proficient and alarmingly quick. They are also capable of other forms of locomotion, but sidewinding seems to be best suited to moving about in their usual sandy habitats. It may also keep them from overheating too quickly, as they leave only two points of contact with the hot surface.[2]
This species is often found climbing in bushes and shrubs, sometimes as much as 2 m above the ground. When it rains, up to 80% of the adult population will climb into bushes and trees. Once, it was observed how some 20 individuals had massed on top of a single cactus or small shrub.[2]
Feeding
It feeds on rodents, lizards, frogs, and a variety of arthropods. Diet may be varied according to availability of prey. High populations in some areas may be due to this generalist diet.[2]
Reproduction
Population from India give birth to live young (viviparous), with young being born from April through August. In Pakistan, they are mostly born in July. A litter may consist of up to 23 young.[2]
Venom
Envenomation results in local symptoms as well as severe systemic symptoms that may prove fatal. Local symptoms include swelling and pain, which appear within minutes of a bite. In very bad cases the swelling may extend up the entire affected limb within 12-24 hours and blisters form on the skin.[9]
Of the more dangerous systemic symptoms, hemorrhage and coagulation defects are the most striking. Hematemesis, melena, hemoptysis, hematuria and epistaxis also occur and may lead to hypovolemic shock. Almost all patients develop oliguria or anuria within a few hours to as late as 6 days post bite. In some cases, kidney dialysis is necessary due to acute renal failure, but this is not often caused by hypotension. It is more often the result of intravascular hemolysis, which occurs in about half of all cases. In other cases, acute renal failure is often caused by disseminated intravascular coagulation.[9]
In any case, antivenin therapy and intravenous hydration within hours of the bite are vital for survival.[9] At least eight different polyvalent and monovalent antivenins are available against bites from this species.[3]
The venom from this species is used in the manufacture of an anticoagulant drug. Even though many other snake venoms contain similar toxins, this particular anticoagulant, called echistatin, is not only especially potent, but also simplistic in structure, which makes it easier to replicate. Indeed, it is obtained not only through the purification of whole venom,[10] but also as a product of chemical synthesis.[11][12]
Subspecies
| Subspecies[5] | Authority[5] | Common name | Geographic range[2] |
|---|---|---|---|
| E. c. astolae | Mertens, 1970 | Astola saw-scaled viper | Pakistan (Astola Island). |
| E. c. carinatus | (Schneider, 1801) | South Indian saw-scaled viper[13] | Peninsular India. |
| E. c. multisquamatus | Cherlin, 1981 | Multiscale saw-scaled viper | From Uzbekistan to Iran in the south and east to western Pakistan. |
| E. c. sinhaleyus | Deraniyagala, 1951 | Sri Lanka. | |
| E. c. sochureki | Stemmler, 1969 | Sochurek's saw-scaled viper | Southern Afghanistan, Pakistan, northern India, southern and central Iran, Oman and UAE. |
See also
Cited references
- ↑ 1.0 1.1 McDiarmid 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).
- ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 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.
- ↑ 3.0 3.1 3.2 Echis carinatus antivenoms at Munich Antivenom Index. Accessed 13 September 2006.
- ↑ Whitaker Z. 1990. Snakeman. Penguin Books Ltd. 192 pp. ISBN 0-14-014308-4.
- ↑ 5.0 5.1 5.2 Echis carinatus (TSN 634967). Integrated Taxonomic Information System. Accessed on 1 August 2006.
- ↑ 6.0 6.1 6.2 Boulenger GA. 1890. The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. Taylor & Francis, London, xviii, 541 pp.
- ↑ 7.0 7.1 7.2 Checklists of the Snakes of Sri Lanka at the Sri Lanka Wildlife Conservation Society
- ↑ Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. ISBN 0-8069-6460-X.
- ↑ 9.0 9.1 9.2 Ali G, Kak M, Kumar M, Bali SK, Tak SI, Hassan G, Wadhwa MB. 2004. Acute renal failure following echis carinatus (saw–scaled viper) envenomation. Indian Journal of Nephrology 14:177-181. PDF at Indian Medlars Centre. Accessed 12 September 2006.
- ↑ Echistatin from Echis carinatus at Sigma-Aldrich. Accessed 29 September 2006.
- ↑ Saw-scaled Vipers at Electronic Medical Curriculum. Accessed 29 September 2006.
- ↑ Garsky VM, Lumma PK, Freidinger RM, Pitzenberger SM, Randall WC, Veber DF, Gould RJ, Friedman PA. 1989. Chemical synthesis of echistatin, a potent inhibitor of platelet aggregation from Echis carinatus: synthesis and biological activity of selected analogs. USA: Proc. Natl. Acad. Sci. Vol.86(11):4022–4026. PDF at PubMed Central. Accessed 29 September 2006.
- ↑ Checklist of Indian Snakes with English Common Names Snakes-Checklist.pdf at University of Texas. Accessed 22 October 2006.
Other references
- Hughes, B. 1976 Notes on African carpet vipers, Echis carinatus, Echis leucogaster and Echis ocellatus (Viperidae, Serpentes). Rev. suisse Zool. 83 (2): 359-371.
- Schneider JG. 1801. Historiae Amphibiorum naturalis et literariae. Fasciculus secundus continens Crocodilos, Scincos, Chamaesauras, Boas. Pseudoboas, Elapes, Angues. Amphisbaenas et Caecilias. Frommani, Jena. 364 pp.
External links
- Species Echis carinatus at the Species2000 Database
- Echis carinatus (image 1) at the Institute of Toxicology and Genetics. Accessed 12 September 2006.
- Echis carinatus (image 2) at the Institute of Toxicology and Genetics. Accessed 12 September 2006.
- Echis carinatus (image 3) at the Institute of Toxicology and Genetics. Accessed 12 September 2006.
- Echis carinatus (Saw-Scaled Viper) SCHNEIDER 1801 at Snakes of Sri Lanka. Accessed 22 October 2006.
