Echis carinatus

Echis carinatus, known as the Sindh saw-scaled viper,<ref name=IUCN/> saw-scaled viper,<ref name=RDB/><ref name="Mal03">Mallow D, Ludwig D, Nilson G (2003). True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. Template:ISBN.</ref> Indian saw-scaled viper, little Indian viper,<ref name="MAVIN">Echis carinatus antivenoms Template:Webarchive at Munich Antivenom Index Template:Webarchive. Accessed 13 September 2006.</ref> and by other common names, is a viper species found in parts of the Middle East and Central Asia, and especially the Indian subcontinent. It is the smallest member of the "big four" Indian snakes that are responsible for causing the most snakebite cases and deaths, due to various factors including their frequent occurrence in highly populated regions, and their inconspicuous nature.<ref name="WhitZ90">Whitaker Z (1990). Snakeman. London: Penguin Books Ltd. 192 pp. Template:ISBN.</ref> Like all vipers, the species is venomous. Two subspecies are currently recognized, including the nominate subspecies described here.<ref name="ITIS">Template:ITIS</ref>

Description

E. c. carinatus, southern India.

The size of E. carinatus ranges between Template:Convert in total length (body + tail), but usually no more than Template:Convert.<ref name="Mal03"/>

Its head is distinct from its neck; its snout is very short and rounded. The nostril is between three shields, and the head is 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 from the supralabials. There are 10–12 supralabials, the fourth usually largest, and 10–13 sublabials.<ref name="Mal03"/><ref name="Bou90">Boulenger GA (1890). The Fauna of British India, Including Ceylon and Burma. Reptilia and Batrachia. London: Secretary of State for India in Council. (Taylor and Francis, printers). xviii + 541 pp. ("Echis carinata", pp. 422-423, Figure 124.)</ref>

Scalation

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.<ref name="Mal03"/><ref name="Bou90"/>

The color-pattern consists of a pale buff, grayish, reddish, olive or pale brown ground color, overlaid mid-dorsally with a series of variably colored, but mostly whitish spots, edged with dark brown, and separated by lighter inter-blotch 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.<ref name="Mal03"/><ref name="Bou90"/>

Common names

• English - saw-scaled viper,<ref name=RDB/><ref name="Mal03"/> Indian saw-scaled viper, little Indian viper.<ref name="MAVIN"/>
• Tamil - surattai pambu.<ref name="SWCS"/> viriyan pamboo, surutai vireyan<ref name="Daniels"/> ( சுருட்டை விரியன் )
• Sinhala - vali polonga (වැලි පොලඟා).<ref name="SWCS">Checklists of the Snakes of Sri Lanka Template:Webarchive at the Sri Lanka Wildlife Conservation Society Template:Webarchive. Accessed 15 August 2007.</ref>
• Odia - Dhuli Naga.<ref name="Daniels"/>
• Pushtu - phissi.<ref name="Daniels">Daniels JC (2002). The Book of Indian Reptiles and Amphibians. Mumbai: Bombay Natural History Society & Oxford University Press. 252 pp. [151-153]. Template:ISBN.</ref>
• Telugu - Chinna pinjara, pinjara
• Sindhi - kuppur, janndi.<ref name="Daniels"/>
• Marathi - phoorsa ([फुरसं]).<ref name="Daniels"/>
• Kannada - kallu haavu.<ref name="Daniels"/>
• Malayalam - anali അണലി<ref name="Daniels"/>
• Gujarati - tarachha, zeri padkoo (ઝેરી પૈડકુ) udaneyn.<ref name="Daniels"/>
• Hindi - aphai (अफई)<ref name="Daniels"/>
• Russian - peschanaya efa (песчаная эфа)<ref name="ЭФА ПЕСЧАНАЯ">эфа песчаная Template:Webarchive at Floranimal.ru Template:Webarchive. Accessed 21 September 2008.</ref>
• Iraqi Arabic - ḥayyat sayyid dakhīl (حية سيد دخيل)<ref>Template:Cite web</ref>
• Persian - mār-e ja'fari (مار جعفری)
• Bengali - fursa boda sap (ফুরসা বোড়া সাপ), also কাঁটা-আঁইশা বোড়া, খুঁদে চন্দ্রবোড়া, বোড়া সাপ, বঙ্করাজ।
• Tulu - netter mugel (ನೆತ್ತೆರ್ ಮೂಗೇಲ್)

Geographic range

Echis carinatus is endemic to Asia. On the Indian subcontinent it is found in India, Sri Lanka, Bangladesh, and Pakistan (including Urak near Quetta and Astola Island off the coast of Makran). In the Middle East it is found in Oman, Masirah (Island), eastern United Arab Emirates, Iraq, and southwestern Iran. In Central Asia it is found in Afghanistan, Uzbekistan, Turkmenistan, and Tajikistan.<ref>Template:Cite web</ref>

The type locality was not included in the original description by Schneider (1801). However, a locality had been given as "Arni" (India) by Russell (1796:3).<ref name="McD99"/>

There are also reports that this species occurs in Iraq.<ref name="Black5">Snakes and Spiders Template:Webarchive at Black Five Template:Webarchive . Accessed 6 January 2007.</ref><ref name="JCS02">Joint Chiefs of Staff Campaign Analysis Report, Snakes & Scorpions in Iraq & Antivenin Sources.pdf Venomous Snakes and Scorpions in Iraq, and Their Antivenin SourcesTemplate:Dead linkTemplate:Cbignore at 311th Human Systems Wing, Brooks City-Base Template:Webarchive. Accessed 6 January 2007.</ref> It is found in Thiqar and Kirkuk governorates.<ref>Template:Cite web</ref>

Habitat

Satara, Maharashtra

Echis carinatus is found on a range of different substrates, including sand, rock, soft soil and in scrublands. It is often found hiding under loose rocks. Specimens have also been found in Balochistan at altitudes of up to 1982 m.<ref name="Mal03"/>

Behaviour

E. carinatus sidewinding.

Echis carinatus is mostly crepuscular and nocturnal, although there have been reports of activity during daylight hours.<ref name="Mal03"/> During the daytime they hide in various locations, such as deep mammal burrows, rock fissures and 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.<ref name="Meh87">Mehrtens JM (1987). Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. Template:ISBN.</ref> 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 that approximately 20 individuals had massed on top of a single cactus or small shrub.<ref name="Mal03"/>

Echis carinatus is one of the species responsible for causing the most snakebite cases due to their inconspicuous and extremely aggressive nature. Its characteristic pose, a double coil with a figure of eight, with the head poised in the center, permits it to lash out like a released spring.<ref name="Daniels"/>

They move about mainly by 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 there are only two points of contact with the hot surface in this form of locomotion.<ref name="Mal03"/>

In the northern parts of its range, these snakes hibernate in winter.<ref name="Daniels"/>

Feeding

Echis carinatus feeds on rodents, lizards, frogs, and a variety of arthropods, such as scorpions, centipedes and large insects.<ref name="Daniels"/> Diet may be varied according to availability of prey. High populations in some areas may be due to this generalist diet.<ref name="Mal03"/>

Reproduction

The population of E. carinatus in India is ovoviviparous. In northern India, mating takes place in the winter with live young being born from April through August. Occasionally, births have also been recorded in other months. A litter usually consists of 3 to 15 young that are 115–152 mm in length.<ref name="Daniels"/> Mallow et al. (2003) mention a maximum litter size of 23.<ref name="Mal03"/>

Juvenile Saw Scaled Viper in a house in Nagrota, J&K.

Venom

Echis carinatus produces on average about 18 mg of dry venom by weight, with a recorded maximum of 72 mg. It may inject as much as 12 mg, whereas the lethal dose for an adult is estimated to be only 5 mg.<ref name="Daniels"/> 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 severe cases the swelling may extend up the entire affected limb within 12–24 hours and blisters form on the skin.<ref name="Ali04">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 J. Nephrol. 14: 177-181. PDF Template:Webarchive at Indian Medlars Centre Template:Webarchive. Accessed 12 September 2006.</ref> The venom yield from individual specimens varies considerably, as does the quantity injected per bite. The mortality rate from their bites is about 20%, and due to the availability of the anti-venom, deaths are currently quite rare.<ref name="Daniels"/>

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 kidney injury (AKI), 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, ARF is often caused by disseminated intravascular coagulation.<ref name="Ali04"/>

In any case, antivenin therapy and intravenous hydration within hours of the bite are vital for survival.<ref name="Ali04"/> At least eight different polyvalent and monovalent antivenins are available against bites from this species.<ref name="MAVIN"/><ref>Template:Cite journal</ref>

The venom from this species is used in the manufacture of several drugs. One is called echistatin, which is an anticoagulant. Even though many other snake venoms contain similar toxins, echistatin is not only especially potent, but also simple in structure, which makes it easier to replicate. Indeed, it is obtained not only through the purification of whole venom,<ref name="SA">Echistatin from Echis carinatusTemplate:Dead link at Sigma-Aldrich. Accessed 29 September 2006.</ref> but also as a product of chemical synthesis.<ref name="EMC">Saw-scaled Vipers Template:Webarchive at Electronic Medical Curriculum Template:Webarchive. Accessed 29 September 2006.</ref><ref name="Gar89">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". Proc. Natl. Acad. Sci. 86 (11): 4022–4026. PDF Template:Webarchive at PubMed Central . Accessed 29 September 2006.</ref> Another drug made from E. carinatus venom is called ecarin and is the primary reagent in the ecarin clotting time (ECT) test, which is used to monitor anticoagulation during treatment with hirudin.<ref name="Fab01">Fabrizio MC (2001). "Use of Ecarin Clotting Time (ECT) with Lepirudin Therapy in Heparin-Induced Thrombocytopenia and Cardiopulmonary Bypass". J. American Soc. Extracorporeal Tech. 33: 117–125. PDF Template:Webarchive at Journal of The American Society of ExtraCorporeal Technology Template:Webarchive. Accessed 5 June 2007.</ref><ref name="TET">Textarin/Ecarin Time at Specialty Laboratories. Accessed 5 June 2007.</ref> Yet another drug produced from E. carinatus venom is Aggrastat (Tirofiban).

Subspecies

Subspecies<ref name="ITIS"/>	Taxon author<ref name="ITIS"/>	Common name	Geographic range<ref name="Mal03"/>
E. c. carinatus	(Schneider, 1801)	South Indian saw-scaled viper<ref name="CIS">Checklist of Indian Snakes with English Common Names [1] Template:Webarchive at University of Texas Template:Webarchive. Accessed 22 October 2006.</ref>	Peninsular India.
E. c. sochureki	Stemmler, 1969	Sochurek's saw-scaled viper	Southern Afghanistan, Pakistan, northern India, southern and central Iran, Oman and UAE.

Further reading

• Boulenger GA (1896). Catalogue of the Snakes in the British Museum (Natural History). Volume III., Containing the ... Viperidæ. London: Trustees of the British Museum (Natural History). (Taylor and Francis, printers). xiv + 727 pp. + Plates I.- XXV. (Echis carinatus, pp. 505–507).
• Das I (2002). A Photographic Guide to Snakes and other Reptiles of India. Sanibel Island, Florida: Ralph Curtis Books. 144 pp. Template:ISBN. (Echis carinatus, p. 61).
• 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. Jena: F. Frommann. vi + 374 pp. + Plates I-II. (Pseudoboa carinata, new species, pp. 285–286). (in Latin).
• Smith MA (1943). The Fauna of British India, Ceylon and Burma, Including the Whole of the Indo-Chinese Sub-region. Reptilia and Amphibia. Vol. III.—Serpentes. London: Secretary of State for India. (Taylor and Francis, printers). xii + 583 pp. (Echis carinatus, pp. 487–490, Figure 154).
• Wall F (1921). Ophidia Taprobanica or the Snakes of Ceylon. Colombo, Ceylon [Sri Lanka]: Colombo Museum. (HR Cottle, Government Printer). xxii + 581 pp. (Echis carinatus, pp. 531–546, Figures 93-95).

External links

• Echis carinatus at Snakes of Sri Lanka. Accessed 22 October 2006.
• Template:Mazuch