Sri Lanka's venomous snakes and their habitat

@ The Island  By Aryadasa Ratnasinghe

According to Sri Lanka National Museum's Manuscript Series (Vol. VIII) and the Sinhala Palm Leaf Manuscripts Medical Vol. IV (Treatment for snake bites), there are five kinds of venomous snakes in Sri Lanka. They are the Mapila (Cat-snake), the Karawala (Krait), the Naya (Cobra), the Tit-polonga (Russell's viper) and the Kunakatuwa (Humped-nose viper).

For purpose of identity, they have been described as follows: ''The mapila's pupil of the eye is vertical and slit-like, the neck is narrower than the head and the body is usually compressed. The row of scales along the top of the back is enlarged, Mapilas are tree-dwelling snakes of which four species are found in Sri Lanka. Some are light-brown, others are dark-brown or light-red, and they either possess dark cross bars or blotches, or lack such markings. They are venomous.

''The karawala is identified by the enlarged row of scales along the top of its back, and by the third upper lip-scale touching the nasal-scale and the eye. It is black in colour with a series of white rings that disappear with age. They are highly venomous.
 

''The naya possesses an expansible hood carrying a spectacles-shaped marking on its upper surface, and the third upper lip-scale, and touches the nasal-scale and the eye. They are highly venomous. They have cylindrical bodies with long tails and smooth scales.

Tit polonga

''The head of the tit-polonga is wider than the neck and its top is covered with small scales, the nostril is large, and a large scale exists over each eye. Along the back is a row of 22 to 24 elliptical markings up to above the base of the tail, and a row of fig-shaped lateral blotches. It is highly venomous.

''The kunakatuwa has the front half of the top of the head covered with large scales and possesses a pit between the nostril and the eye, a small bump exists at the tip of its snout. Its markings are irregular blotches either on a brown, pink, grey or yellow background. It is venomous but rarely fatal''.

''These snakes as well as other reptilia belong to the natural order Ophidia. They are characterized by an elongated limbless body possibly evolved because it is advantageous in progression through dense vacation. One of the most striking internal modifications is the absence or greatly reduced size of the left lung. It is said that there are some 3,000 species of snakes found in the tropics and temperate zones, but none in New Zealand, Ireland, Iceland and near the poles.

The skin of the snake is covered with scales which are markedly wider underneath where they form, in all except a few species, an essential aid for movement, e.g., a snake is helpless on glass where these scales can effect no grip on the surface. Its progression may be undulant, concerting or creeping, or a combination. Detailed vision is limited at a distance, though movement is immediately seen. Hearing is restricted to ground vibrations, and sound waves are not perceived as with other animals.

The sense of touch is acute. Besides the sense of smell through the nasal passages, the flickering tongue picks up airborne particles which are then passed on to special organs in the mouth for investigation. Some snakes, e.g., the rattlesnakes have a cavity between eye and nostril which is very sensitive to infra-red rays, useful in locating warm-blooded prey in the dark. All snakes are carnivorous, and often camouflaged for better concealment in hunting as well as their own protection. Some snakes are oviparous and others ovoviviparous (the eggs are retained in the oviducts until development is complete). In both cases the young are immediately self-sufficient.
The majority of snakes belong to the family Colubridae. They are chiefly harmless, e.g., the 'garandiya' (rat-snake) which even enters into houses to feed on rats that live on the roofs. Its bite is not venomous but has some toxicity requiring medical attention. According to the native method of treatment for snake bites, the 'sarpa-vederala', who has specialised in the art, makes prognostications by studying the messenger who comes to summon him, his behaviour and costume, and whether the victim will arrive or not.

Cure

The realm of treatment of the native physician in regard to snake bites is known as 'agada-tantra', which includes medicine, charms, herbal preparations, poultices, fomentation, medicaments, errhines, medicinal oils, 'gulis', 'kalkas' etc. used to neutralize the effects of venom ingested into the body by venomous reptilia. Their families includes the Elapidae, (the cobra, the coral snakes and the death adder). The Viperidae belongs to the family of vipers. The Hydrophydae are the aquatic sea-snakes.

Among the snakes found in Sri Lanka, the most venomous and the most feared is the cobra, popularly known as the 'naya', which is highly respected, sometimes honoured and even worshipped by those who consider cobras with high esteem. If a person were to come across a cobra by accident, he speaks to it nicely to move away from the path, and never attacks it or tries to chase it away. There is a saying that a cobra never bitesa blind man, even if he were to tread upon it by accident. This is said to be a sublime quality of cobras.
Cobra belongs to the genus 'Naja' because of its ability to dilate its broad hood. The Indian cobra (Naja Naja tripudians) or cobra de capello, as the Portuguese knew it, attains a length of about seven feet. The king cobra (Naja hannah bungarus), mostly found in the African wilderness, grows toa length of about fourteen feet, and it is said to be the fiercest and the most aggressive of snakes. It is yellowish-brown or olive in colour, with black crossbands, and feeds on other reptilia. African cobras include the asp (Naja haje) and the black-necked cobra (Naja nigricollis).

The cobras, generally, bite during daytime or as dusk falls, and rarely or never by night. As night falls they move into their shelters. During the day, they lie under grass or jungle undergrowth awaiting for prey, and ready to attack at any moment when they are disturbed or harmed. Vipers roam in the dark for prey and go into their hiding places at dawn. This natural instinct is woven into the fabric of folklore to prove that they are antagonistic towards each other. The Sinhala proverb 'Nayayi polongai vage' (Like cobra and wiper) refers to those who hate each other. As vipers move by night, they never meet cobras unless by accident.


Robert Knox

Robert Knox, writing in 1681, what he had heard during his stay in the Kandyan kingdom for 20 years, about the folklore, says ''The reason and original of this fatal enmity between these two Serpents, is this according to a Fable among the Chingulays (Sinhalese). These two chanced to meet in a dry season, when water was scarce. The Polonga (viper) being almost famished for thirst, asked the Naya (cobra) where he might go to find a little water.

''The Naya a little before had met with a bowl of water in which a child lay playing. As it is usual among this people to wash their children in a bowl of water, and there leave them to tumble and play in it. Here the Noya quenched his thirst, but as he was drinking, the child that lay in the bowl, out of his innocence and play, hit him on the head with his hand, which the Noya made no matter of, but bare patiently, knowing it was not done out of any malice: and having drunk as much as sufficed him, went away without doing the child any harm.

''Being minded to direct the Polonga to this bowl, but desirous withal to preserve the child, he told him, that he knew of water but that he was such a surely hasty creature, that he was fearful to let him know where it was, lest he might do some mischief; making him therefore promise that he would not, he then told him that at such a place there was a bowl of water with a child playing in it, and that probably the child might, as he was tumbling give him a pat on the Head, as he had done to him before, but charged him nevertheless not to hurt the child, which the Polonga having promised went his way towards the water, as the Noya had directed him.

''The Noya knowing his touchy disposition went after him, fearing he might do the child a mischief, and that thereby he himself might be deprived of the like benefit afterwards. It fell out as he feared. For as the Polonga drank, the child patted him on the head, and he in his hasty humour bit him on the hand and killed him. The Noya seeing this resolved to be revenged, and so reproaching him for his baseness, fought him so long till he killed him. And after that devoured him, which to this day they ever do, always fight when they meet, and the conqueror eats the body of the vanquished''. This enmity is said to be an everlasting phenomenon between the two.
Dr. John Davy, writing in 1821, about snakes says: ''Whilst I was in Ceylon (Sri Lanka), my professional pursuits led me to pay particular attention to the snakes of the island, especially to those whose bite is poisonous. It is the common belief that the country abounds in snakes and that they are very dangerous. All this is greatly exaggerated. I have procured twenty different kinds of snakes and of them, sixteen were harmless, though the majority has the character of being venomous. The four poisonous snakes were all of the coluber kind''.

Writing about the cobra, he says ''This coluber naja of Linnaeus, is too well known to require description. The natives in general rather venerate this snake than dread it. They believe that it belongs to another world, i.e., the nagaloka, and when it appears on earth, it is merely a visitor. Frequent exhibitions are made of this snake by men called 'snake-charmers'. They irritate the snake by striking it, and avoid with great agility the attacks aimed at them and thus play without dread, and with impunity, with danger.''

Common belief

The common belief is that the poisonous fangs of the cobras, exhibited by the snake-charmers, have been extracted for purpose of safety. But, Dr. Davy says ''I have examined the snakes, I have seen exhibited, and have found their poisonous fangs in and uninjured. These men do possess a charm, and it is the confidence and courage, acquainted with the habits and disposition of cobras. Any one possessing the confidence and agility of these men may imitate them, and I have made the trial more than once.

''The reputation that many Indian medicines for snake bites have snake-stones still exists. I have examined them carefully and found them to be pieces of partially burnt bones, some of chalk and some resembled bezoars, consisting chiefly of vegetable matter.'' Bezoars are stony concretions found in the stomachs of goats, antelopes, llamas, chamois, etc., formerly esteemed as an antidote to all poisons.
Venom involves multiple toxic reactions in man occurring simultaneously. Accordingly to medical opinion, most viper venoms are vasculotoxic, causing a rapidly swelling of the area around the portal entry of venom. This swelling is presumably due to diffused venom passing through the tissues and affecting vascular permeability. ''Local necrosis in viper bites is mainly ischaemic. The clotting of blood blocks the blood vessels causing dry gangrene, but in cobra bites it causes wet gangrene with a putrid smell''.

Among most victims bitten by venomous snakes, shock is believed to be the cause of death, when they become aware that their lives are at stake. This fear is followed by emotional symptoms, such as faintness, stupor, feeble pulse and shallow breathing, which are distinguished from systemic envenoming. These symptoms appear rapidly within minutes after the bite, whereas systemic poisoning is delayed by one hour or more. However, early collapse is sometimes due to high potency of the venom ingested and not due to fear of death.

First signs

It has been pointed out that ptosis (drooping of the upper eye-lids) is usually the first sign of a cobra bite. In viper bite poisoning, the earliest sign is blood spit which becomes stained within 15 minutes after the bite. Bleeding from gums and discolouration of blood may follow within 3 hours.

Urine becomes discoloured due to the presence of myoglobin and death may occur due to cardiac arrest or renal failure.
According to native clinical pathology pertaining to snake bites the symptoms are: ''discoloration of the body, finger-nails and faeces; pain at the joints; teeth become discoloured; yawns too often, mucous flows from mouth; neck becomes lifeless; body pain develops with a burning sensation; low urine flow; headache, vomiting, redness in eyes; lack of appetite giddiness; hiccough, thirstiness, dryness of mouth, altered voice, constipation; exudations from mouth, eyes and ears, and other symptoms associated with envenoming. Swelling due to cobra bite develops more slowly than viper bite.

Public opinion still holds that native treatment is better than western treatment to save victims from the danger of being bitten by venomous reptilia. In most rural areas, the 'sarpa-vederala' has his place as the saviour of mankind bitten by snakes and on the verge of death. ''In western treatment broad spectrum antibiotics are used to minimize the risk of local infection, and antivenom injections are given, diluted with isotonic saline, to inactivate the venom. Specific antivenom is desirable, but if the snake is unknown, polyvalent serum may be given''. So says Dr. Stamm.