Saw-scaled viper

Identification

The saw-scaled viper is a small viper with a short, rounded snout, large eyes and strongly keeled scales. It is pale brown, grey or sandy above, with a row of pale, dark-edged spots along the back and a wavy light line along each side. There is usually a whitish cross- or arrow-shaped mark on top of the head¹.

Colour varies from brown and olive to reddish, orange or greyish, and the eyes have vertical pupils². Adults are usually up to about 60 cm long; the largest recorded in Smith’s (1943) account measured about 76 cm¹.

Distribution

The saw-scaled viper is found in India, Sri Lanka, Pakistan, Afghanistan, Iran, Oman, the United Arab Emirates, Qatar, Turkmenistan, Uzbekistan and Tajikistan³. It is not known from Bangladesh³.

Two subspecies are recognised. E. c. carinatus lives in peninsular India and Sri Lanka, while E. c. sochureki occurs in northern and north-western India, Pakistan, Afghanistan, Iran and parts of Arabia. Some researchers have proposed treating sochureki as a separate species, but this is still debated³. WHO guidelines describe sochureki as the larger, northern subspecies⁴.

Habitat

This is mainly a snake of dry country. It is common in semi-desert areas with sandy, poor soil and sparse vegetation, but avoids dense jungle. It shelters under stones and in cracks in rocks, and has been found up to about 1,800 m in Baluchistan¹.

In southern India it lives in dry deciduous forest, scrub jungle, grassland and rocky areas, usually hiding under rocks and around small bushes².

Behaviour

The saw-scaled viper is mainly nocturnal², but it may also lie in the sun, even in very hot weather¹. It can move quickly to escape and strikes very fast when provoked¹.

When alarmed it bends its body into coils shaped almost like a figure 8 and rubs them together. The saw-edged keels on its side scales make a rasping, hissing sound¹. WHO guidelines describe this “grating rasp” as a warning sound that can identify the snake even in the dark, and list the species among snakes that are quick to strike when disturbed⁴.

Diet

The saw-scaled viper eats a wide range of prey, including rodents, lizards, frogs and many arthropods such as scorpions, centipedes and large insects⁵.

In the Thar Desert of Rajasthan, the stomachs of two road-killed E. c. sochureki contained an Indian desert gerbil and a large camel spider, showing that these small vipers can take surprisingly varied prey⁵.

Reproduction

Unlike other Echis species, which lay eggs, the saw-scaled viper gives birth to live young³. Smith (1943) reported 3–12 young per litter, born in April to June in the Bombay region¹.

Litters of up to 23 have been reported from Iran. Newborn snakes measure about 11.5–15 cm. In August 2018, a female in Madurai, Tamil Nadu, was found with nine newborn young under a rock².

Venom and medical significance

The saw-scaled viper is one of India’s “big four” medically important snakes, with the Indian cobra, common krait and Russell’s viper⁴. Its bite typically causes local pain and swelling and problems with blood clotting. Its venom contains enzymes that activate prothrombin, using up clotting factors so that the blood may not clot, which can lead to dangerous bleeding⁴.

About 5–10% of bites cause no symptoms of envenoming⁴, but every bite must be treated as serious. Bites by the northern subspecies E. c. sochureki may need larger antivenom doses⁴, and some have responded poorly to the current Indian polyvalent antivenom⁵. Anyone bitten must go to hospital immediately.

Conservation

The saw-scaled viper is listed as Least Concern on the IUCN Red List (assessed 2021)⁶. Smith (1943) described it as incredibly common in many districts of India¹.

In India it is protected under Schedule II of the Wild Life (Protection) Act, 1972, as amended in 2022, which covers all vipers not listed in Schedule I⁷.

Similar species

The saw-scaled viper can be confused with other brown vipers, such as Russell’s viper (Daboia russelii), and WHO guidelines note that bites by the hump-nosed pit viper (Hypnale hypnale) have been mistaken for saw-scaled viper bites⁴.

Some differences: Russell’s viper has neat rows of large, dark-rimmed, pale-centred spots, and it gives a blowing hiss rather than the rasping sound of the saw-scaled viper⁴. The saw-scaled viper is small, has rough, strongly keeled scales and a pale cross- or arrow-shaped mark on its head¹. These differences are not a safe basis for handling any snake.

In captivity

The saw-scaled viper is dangerously venomous and is not suitable as a pet. In India it is listed in Schedule II of the Wild Life (Protection) Act, 1972 (as amended in 2022), and the Act prohibits hunting animals listed in Schedules I and II⁷.