Echis carinatus, known as the saw-scaled viper,[2]Indian saw-scaled viper, little Indian viper,[3] and by other common names, is a viperspecies 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.[4] Like all vipers, the species is venomous. Two subspecies are currently recognized, including the nominate subspecies described here.[5]
The size of E. carinatus ranges between 38 and 80cm (15 and 31in) in total length (body + tail), but usually no more than 60cm (24in).[2]
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.[2][6]
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.[2][6]
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 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]
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).[1]
There are also reports that this species occurs in Iraq.[11][12] It is found in Thiqar and Kirkuk governorates.[13]
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.[2]
Behaviour
E. carinatus sidewinding.
Echis carinatus is mostly crepuscular and nocturnal, although there have been reports of activity during daylight hours.[2] 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.[14] 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.[2]
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.[8]
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.[2]
In the northern parts of its range, these snakes hibernate in winter.[8]
Feeding
Echis carinatus feeds on rodents, lizards, frogs, and a variety of arthropods, such as scorpions, centipedes and large insects.[8] Diet may be varied according to availability of prey. High populations in some areas may be due to this generalist diet.[2]
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 115–152mm in length.[8] Mallow et al. (2003) mention a maximum litter size of 23.[2]
Juvenile Saw Scaled Viper in a house in Nagrota, J&K.
Venom
Echis carinatus produces on average about 18mg of dry venom by weight, with a recorded maximum of 72mg. It may inject as much as 12mg, whereas the lethal dose for an adult is estimated to be only 5mg.[8] 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.[15] 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.[8]
In any case, antivenin therapy and intravenous hydration within hours of the bite are vital for survival.[15] 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 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 simplistic in structure, which makes it easier to replicate. Indeed, it is obtained not only through the purification of whole venom,[16] but also as a product of chemical synthesis.[17][18] 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.[19][20] Yet another drug produced from E. carinatus venom is Aggrastat (Tirofiban).
Antivenoms have been developed to treat saw-scaled viper bites.[21]
Southern Afghanistan, Pakistan, northern India, southern and central Iran, Oman and UAE.
Related Research Articles
Antivenom, also known as antivenin, venom antiserum, and antivenom immunoglobulin, is a specific treatment for envenomation. It is composed of antibodies and used to treat certain venomous bites and stings. Antivenoms are recommended only if there is significant toxicity or a high risk of toxicity. The specific antivenom needed depends on the species involved. It is given by injection.
Bungarus is a genus of venomous snakes in the family Elapidae. The genus is native to Asia. Often found on the floor of tropical forests in South Asia, Southeast Asia and Southern China, they are medium-sized, highly venomous snakes with a total length typically not exceeding 2 metres. These are nocturnal ophiophagious predators which prey primarily on other snakes at night, occasionally taking lizards, amphibians and rodents. Most species are with banded patterns acting as a warning sign to their predators. Despite being considered as generally docile and timid, kraits are capable of delivering highly potent neurotoxic venom which is medically significant with potential lethality to humans. The genus currently holds 18 species and 5 subspecies.
Russell's viper is a highly venomous snake in the family Viperidae native to South Asia. It was described in 1797 by George Shaw and Frederick Polydore Nodder. It is named after Patrick Russell and is one of the most dangerous big four snakes in India.
Bitis is a genus of vipers found in Africa and the southern Arabian Peninsula. It includes the largest and the smallest vipers in the world. Members are known for their characteristic threat displays that involve inflating and deflating their bodies while hissing and puffing loudly. The type species for this genus is B. arietans, which is also the most widely distributed viper in Africa. Currently, 18 species are recognized.
The four venomous snake species responsible for causing the greatest number of medically significant human snake bite cases on the Indian subcontinent are sometimes collectively referred to as the Big Four. They are as follows:
Russell's viper, Daboia russelii
Common krait, Bungarus caeruleus
Indian cobra, Naja naja
Indian saw-scaled viper, Echis carinatus
Hypnale is a genus of pit vipers endemic to Sri Lanka and southwestern India. Three monotypic species are currently recognized. All members have more or less upturned snouts that produce a hump-nosed effect.
The Indian cobra, also known commonly as the spectacled cobra, Asian cobra, or binocellate cobra, is a species of cobra, a venomous snake in the family Elapidae. The species is native to the Indian subcontinent, and is a member of the "big four" species that are responsible for the most snakebite cases in India.
Atheris is a genus of vipers known as bush vipers. They are found only in tropical subsaharan Africa and many species have isolated and fragmented distributions due to their confinement to rain forests. Like all other vipers, they are venomous. In an example of convergent evolution, they show many similarities to the arboreal pit vipers of Asia and South America. Seventeen species are currently recognized.
Echis is a genus of vipers found in the dry regions of Africa, the Middle East, India, Sri Lanka and Pakistan. They have a characteristic threat display, rubbing sections of their body together to produce a "sizzling" warning sound. The name Echis is the Latin transliteration of the Greek word for "viper" (ἔχις). Like all vipers, they are venomous. Their common name is "saw-scaled vipers" and they include some of the species responsible for causing the most snakebite cases and deaths in the world. Twelve species are currently recognized.
Hypnale hypnale is a venomous pit viper species endemic to India and Sri Lanka. Common names include the hump-nosed viper, Merrem's hump-nosed viperhump-nosed pit viper, and Oriental hump-nosed viper.
Calloselasma is a monotypic genus created for a pit viper species, Calloselasma rhodostoma, which is endemic to Southeast Asia from Thailand to northern Malaysia and on the island of Java. No subspecies are currently recognized.
Echis ocellatus, known by the common names West African carpet viper and ocellated carpet viper, is a highly venomous species of viper endemic to West Africa. No subspecies are currently recognized.
Echis pyramidum, known as the Northeast African carpet viper, Egyptian saw-scaled viper, and by other common names, is a species of viper endemic to Northeast Africa and the Arabian Peninsula. Like all other vipers, it is venomous. Three subspecies are currently recognized, including the nominate subspecies described here.
Echis carinatus multisquamatus, known as the multiscale saw-scaled viper and transcaspian saw-scaled viper, is a viper subspecies found in Uzbekistan, Turkmenistan, Iran, Afghanistan, and Pakistan. Like all other vipers, it is venomous.
Echis carinatus sinhaleyus is a venomous viper subspecies endemic to Sri Lanka.
Echis carinatus sochureki is a venomous viper subspecies found in India, Pakistan, Afghanistan, Iran, and parts of the Arabian Peninsula.
Echis pyramidum leakeyi is a venomous viper subspecies endemic to northern East Africa.
The fiery flying serpent is a creature mentioned in the Book of Isaiah in the Tanakh.
References
1 2 McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN1-893777-00-6 (series). ISBN1-893777-01-4 (volume).
1 2 3 4 5 6 7 8 9 10 11 12 13 Mallow D, Ludwig D, Nilson G (2003). True Vipers: Natural History and Toxinology of Old World Vipers. Malabar, Florida: Krieger Publishing Company. 359 pp. ISBN0-89464-877-2.
1 2 3 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.)
↑ 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. PDFArchived 2019-07-01 at the Wayback Machine at PubMed CentralArchived 2008-05-14 at the Wayback Machine . Accessed 29 September 2006.
↑ Lim A, Tan K, Tan C (February 2024). "Immunoreactivity and neutralization efficacy of Pakistani Viper Antivenom (PVAV) against venoms of Saw-scaled Vipers (Echis carinatus subspp.) and Western Russell's Vipers (Daboia russelii) from the Indian subcontinent". Acta Tropica (250): 107099. doi:10.1016/j.actatropica.2023.107099. PMID38097152.
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. ISBN0-88359-056-5. (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).
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