All snakes are commonly considered to be poisonous in the sense that the venom in their saliva is sufficient to kill or paralyze their prey. But in majority of them, their poison can act on small creatures only. Such snakes are harmless to human-beings and may be considered as non poisonous. Unless a definite poison gland, a duct to carry the poison from it and a specialized grooved or tubular tooth, called a Fang, to transport the poison, are present, a snake is not a poisonous one. Only very few of the land snakes are dangerously poisonous to man. These are Cobras, Kraits and Vipers.
Most of other land-snakes are practically harmless to men, though some may be slightly poisonous. All sea-snakes are poisonous.
Naja naja (Linnaeus)
There are ten species of cobra altogether of which 7 are found in Africa, one is peculiar to the Philippines and only two occur in Indian subcontinent. Cobra has a very beautiful appearance but it is a deadly poisonous and dangerous reptile, with an average length of 1371 to 1625mm.
The most prominent characteristic of cobra is its well marked hood. It has long ribs on the neck just behind the head with attached muscles. The hood is formed by the elongated ribs of 3rd and the following 27 vertebrae, the 9th on the left and right are the longest. Another distinguishing feature is the peculiar touching the intranasal having 3rd supralabial in contact with the eye. The hood sometimes bear spectacle mark like V, then they are called spectacled cobra. Cobra is extremely variable in coloration and markings with brownish or black above, with or without black and white mark on the hood, and with one or two black crossbars below hood.
Cobra is eclectic in habitat throughout Indian subcontinent to Southern China in the east and to the Philippines in the south. It occurs in heavy jungles, open cultivated land, in populated are as where old masonry construction form ideal refuge. White ant nests, holes in the ground or the tangle of roots at the base of a tree are particularly favoured. Frequently found near or in water and is a strong swimmer.
Usually not aggressive and often exceedingly timid but occasionally fierce and aggressive when disturbed. Young are much more dangerous than adults more easily excited and ready to strike repeatedly and with determination. If disturbed when close, it erects itself, sways its hood backwards and forwards, hisses and get ready to strike, If the person keeps still it drops its head and glides away quietly but if he makes movement, it again erects its hood and gets ready to strike. The bite of cobra is usually a quick snap but may be tenacious. The poison may trickle on the skin as a drop or may be sprayed and very little may penetrate through t he actual puncture. Cobra is diurnal in habit, during the day it is found roaming about in search of food or drink, It moves fast, feeds on rats, frogs and toads, less frequently on birds and their eggs. Sometimes the cobra itself is eaten by its bigger relative. Mating takes place in January, eggs are laid in April and May, about 45 eggs are laid at a time, which are soft shelled, elongate oval measuring 49x2Bmm. Both parents known to incubate. Hatching occurs after 48-69 days, hatchlings measure 250-280mm, at birth. The poison glands are active from birth. The poison of cobra is very potent and kills a man usually within 2 to 6 hours after the bite.
Common Indian Krait
Bangarus caerulus (Schneider)
Common Indian Krait is found throughout the Indian Peninsular regions from Sindh to west Bengal and in South up to cape, Sri Lanka. It inhabits fields, low scrub jungles and is common in the vicinity of human habitation, often taking up residence inside houses. Frequently found near or in water. It is nocturnal and of a placid temperament biting usually only under provocation. It feeds mainly on snakes including other Kraits. Young feed more or less exclusively on blind snakes occasionally frogs, lizards and small mammals are also taken. It is distinguished by enlarged hexagonal vertebral scales, the entire subcaudals, the uniformly white belly and the narrow white crossbars on the back more or less distinctly in pairs. Body rather long and cylindrical. Eyes rather small, scales shiny, iris black, pupil indistinguishable and short. The body coloration is lustrous black or bluish black above with paired narrow white crossbars are well defined and conspicuous. The male is longer in total length and has a longer tail. Mating occurs in February and March. A disagreeable smell of secretion from anal gland helps in recognition and identification of snakes. Female is known to stay with the eggs, clutch size varies from 6 to 15 eggs each measuring 35x1 9mm. Eggs hatch from May to July. Hatchlings measure 266 to 298mm. The venom of the common Krait is fatal to man and is considered to be fifteen times more virulent than of the cobra and the Krait is one the deadliest among the poisonous snakes of the world. The person bitten is overcome by a creeping paralysis but in addition there is a violent abdominal pain probably due to internal bleeding. The eyelids and lower lip droop and the person is unable to walk and to breathe, death occurs in 6-24 hours after the bite.
Vipera russelli (Shan)
This snake was first brought to the notice of the scientific world by Dr. Patrick Russel in 1796.Hence the name of species is given as russelli.
It is widely distributed throughout Indian subcontinent, from Baluchistan in the west and Kashmir in the north to the eastern Himalayas and eastwards to Burma, Thailand, Indochina, Formosa, Indo Australian Archipelago and Sri Lanka. Usually found in plains but has been recorded up to 2100m in south India and 1800m in the western Himalayas.
It has beautiful and distinctive appearance identified by a combination of characters head covered with small scales and without shields, 27-33 costals at mid body, subcaudals divided.
Body massive, cylindrical, narrowing at both ends, head flat triangular with short Snout, large gold flecked eyes with vertical pupil and large open nostrils. Neck constricted. Belly rounded tail short about 1/7th of the total length. Coloration is brown of various shades with three series of large ovate spots, one vertebral and two costals. Spots brown in the centre and black & white on the margins. Head with distinct dark patch behind, a dark streak margined with white, pink or buff behind eye. A dark stripe from eye to lip. A conspicuous white buff or pink line from gape converges to form a V about snout.
Belly white a few dark half moon marks of the margins of the anterior ventral.
Normally the snake is sluggish and does not strike readily unless irritated when it bites with great malice. The bite may be either a snap or the snake may hold on for many seconds. Largely nocturnal, its movements are slow. The young are more prone to be aggressive and to bite. The main food is rodent, in addition to squirrels, shrews, kittens, small birds calottes, lizards and frogs. Young are often cannibalistic. The Russell\'s viper is viviparous. The young are born alive with clear well marked, dark spots on the back, the young measures 8-11 inches long at birth. They are much more active than the adults and their poison is quite as potent.
It is a prolific snake, 30 to 40 or more being produced in one brood. Frequently the adults are 3-4 ft. long but they may grow up to 51/2 ft. The poison it can inject at one bite is about enough to kill two persons. There is intense pain and a thin red coloured fluid continues to ooze out of the wound. The victim may die in few hours or after some days if not treated properly.
Python molurus (Linnaeus)
Indian Python is a well known and common snake found in Indian subcontinent. It is normally a jungle dweller occurring in dense as well as in open forests with rocky outcrops. In the absence of forests, it occurs in rivers and jheels and feeds on small mammals and birds. It has been known to eat a fully grown leopard.
Python is a large stout snake from 10-15 ft in length and may occasionally grow up to 25 feet.
It is a heavy animal and been known to weigh as much as 250 lbs. It can be easily identified and distinguished from other snakes by presence of sensory pits on the rostral (snout shield) and first two labials (Lip shields). The number of scales in costals range from 58-73, ventrals 245-270, caudal 60-72 pairs. A massively built snake is rounded in outline and thickest in the middle tapering towards head and anus. Scales smooth, and glossy when the snake is in good condition. Neck distinct head flattened with a long snout. Nostrils large, directed upwards and situated high on the snout. Eyes small, pupil vertical, iris flecked with gold. Chin with mental groove. Tail short and prehensile tapering rapidly. Rudimontary hind limbs as curved claws on either side of anus, more highly developed in males. Coloration is ground grayish whitish or yellowish in adults and in the young often very pretty pink shade. A dark streak from eye to nostril in young may or may not be present in adults. A conspicuous dark oblique band from eye to gape. The body is covered with a series of large, roughly quadrate patches from neck to tail dorsally.
Two small rows of marking occur to the side of median row of these patches. Indian Python is lethargic and slow snake with peculiar method of rectilinear progression. They are quite at home in water swim deftly and strongly when necessary but usually remain submerged except for the tip of snout. It hibernates during cold season often in groups. Mating occurs during the cold season in December, January and February when it is in hibernation. Eggs varied in number from 8 to 100 and laid 3-4 months later in hot weather during March, April, May and June. Eggs are white soft and measure 1 2x6cm equally domed at both ends, hatch after 58 days of incubation period. Hatchlings measure 73cm at the time of hatching and become 11 ft long after 5 years.
The skin of python is commercially very important while its flesh is eaten in some parts of the world.
(Contributed by: Conservator of Wildlife, Government of Sindh, Karachi)
To focus world attention on the need to protect and preserve this vulnerable wildlife species Pakistan Postal Services Corporation is issuing a set of four special postage stamps of Rs. 6/-value each depicting different species of snakes on April 15,1995. It is part of the series on wildlife stamps being issued by Pakistan Postal Services Corporation since 1975.