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wikitox:handbook_identification_and_morphological_characteristics

Identification and morphological characteristics

The correct identity of the offending snake species helps the physician to adopt the appropriate management regime. However, often the offending snake is not always available and the physician has to assume the identity of the offending snake by the clinical features, bedside laboratory tests (such as clotting test) and the circumstantial evidence of the bite. Or else, by showing colour illustrations of snakes or specimens preserved in formaldehyde or alcohol to the patient or to accompanying persons who witnessed the bite. Advanced techniques such as venom detection kits (ELISA) are not available in Sri Lanka.

Thus, the physician should be able to identify at least the five following highly venomous snakes of Sri Lanka.

Russell’s viper (Daboia russelli russelli)

The head is triangular and has two white lines on the head which meet at the tip of the snout to form the letter “V”. It has a well defined neck and a vertical pupil. The body is stocky, the dorsal surface is brown in colour and has 3 longitudinal rows of circular or oval shaped dark markings. The main row of markings runs along the mid dorsal line and other two rows on either side of the body. Each spot has an inner black area and an outer white margin. The belly is whitish or yellowish with small dark spots. Young snakes are very bright, beautiful and the body is more slender. A mature adult can grow up to approximately 1 m in length.

Common krait (Bungarus caeruleus)

It is a slender long snake without a distinct neck. A mature adult can grow up to approximately 1.5 meters in length. Dorsal side of the body is highly glossy black or dark bluish in colour and has a series of narrow white paired dorsal bands. In the young, these bands are distinct, but with age these white bands are reduced to vertebral spots, or may disappear completely. The belly is pearly white. The mid dorsal scales (vertebral) are hexagonal and larger than the rest. The subcaudals or the scales on the ventral aspect of the tail are uniserial or of single scales. These features will help to identify the krait from other non venomous snakes which resemble the krait.

Ceylon krait (Bungarus ceylonicus)

The morphological features are similar to the common krait. However, there are 15-25 distinct single white crossbars on the dorsal aspect, which run across the belly, alternately with black bands. However, as the snake gets older these bands are reduced to vertebral spots, or may disappear completely. The belly is white in the young but is alternately black and white in adults, with the black bands being broader. The mid dorsal scales are hexagonal and larger than the rest and the ventral tail has single scales. These two features are important to distinguish it from other snakes. It is generally smaller than the common krait and can grow up to 1 meter in length.

Cobra Merrem's (Naja naja)

Sri Lankan cobra is now considered a distinct species and not a subspecies. It can attain maximum length about 2 m and has a distinct hood (with highly variable markings). However, the most characteristic is the spectacle mark on the dorsal aspect of the hood. The ventral side of the hood has two symmetrical black spots, which is a constant feature seen in all Sri Lankan cobras. The body is brown with thin white bars. The belly has light or dark cross bands which might disappear with age.

Hump-nosed viper (Hypnale hypnale)

The head is triangular and flat, and the snout ends in a wedge or hump like prominence. A distinct pit called loreal pit is visible between the eye and the nostril. The body is stocky and the dorsal surface is muddy brown in colour. A series of dark brown oval spots are seen on either side of the spine. Ventral aspect is off white and occasionally mottled with brown. The snake can grow up to 45 cm in length.

/home/wikitoxo/public_html/data/pages/wikitox/handbook_identification_and_morphological_characteristics.txt · Last modified: 2018/09/01 09:01 (external edit)