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Malayan Museum Pamphlets

Popular Pamphlet No. II

PO.lSONOUS SNAKES IN MALAYA

by

M. W. F. Tweedie, M.A. , C.M.Z.S.

Director, Raffles Museum

and

H. A. Reid, M.B. (Edin.), M.R.C.P.E., D.T.M. & H.

Specialist Physician, Federation of Malaya

The Malayan Pit Viper

KP JB 1938

Price : 50 cents

PERPUSTAKAAN NEGARA MALAYSIA

Poisonous Snakes ill Malaya I

POISONOUS SNAKES are nowhere abundant in Malaya and the hazard of snake bite is not a serious one. This generalisation is equally true of cultivated land and the wildest jungle. It is not entirely applicable to the coastal and estuarine waters surrounding the country, as some kinds of sea snakes are abundant and most of them dangerously venomous. However, victims are virtually confined to fishermen and their kin.

The great contrast in the incidence of snake bite in Malaya and in the countries of continental Asia, especially India, is probably largely due to the absence in our country of two very dangerous vipers, the Saw-scaled Viper (Echis carinatus) and the Russell's Viper (Vipera russellt). The former is a snake of hot deserts and certainly does not occur in Malaya; Russell's Viper is found in Thailand and it is not impossible that it may extend into the northern-most Malay States, but it has never been recorded from this country. Both these vipers are sluggish and disinclined to move when approached, and may be abundant where they are found. This is especially true of the Sawscaled Viper, which is responsible in India for many deaths every year.

The bite of a poisonous snake is inflicted by a pair of enlarged teeth situated at the front of the upper jaw. These are hollow and perforated at the tip like a hypodermic needle, and connected at the base by a duct to a gland which secretes the venom. The tongue of the snake, which is constantly flicked in and out by many species, is a sensory organ and has nothing whatever to do with the reptile's venomous properties.

The natural purpose of the venom is to kill or paralyse a struggling victim taken as prey, and thereafter serve as a digestive ferment. As a weapon of defence it is of little use except as a threat, since its action is never so rapid that a relatively large animal, bitten by a snake, has not plenty of time to deal with the author of the bite before it is incapacitated. Probably for this reason most venomous snakes display warning coloration or behaviour such as the conspicuous banding and bright colours of the kraits and coral makes and the well known spreading of the cobra's hood. The purpose of this type of display is to convey the message: "You can attack and kill me easily, but if you do it will be the worse for you."

Malayan Poisonous Snakes. Exclusive of the true Sea Snakes a total of 111 different species of snakes is known to inhabit the land and the fresh and tidal waters of this country. Of these, sixteen are venomous, but only five of them need be considered dangerous. None of the venomous species are particularly abundant, and it is a fact that the great majority of snakes encountered on land in Malaya are hal1llless. About seventeen species of sea snakes, all venomous, are found aroun<i @~r coasts.

1 This pamphlet deals with snakes only from the point of view thllt they are poisonous animals. A comprehensive account of Malayan snakes is given in The Snakes of Malaya by M. W. F. Tweedie, Government Printing Office, Singapore, 1953. $5.


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The venomous snakes of the land belong to two very distinct families, the Elapidae, comprising the Cobras, Kraits and Coral Snakes, and the Viperidae or Vipers. These and the Hydrophiidae or Sea Snakes are briefly described below.

The entire head and body of a snake is covered with scales. Those on the back and sides are small and usually overlapping, the ones on the belly are generally broad and mayor may not span the width of the body; they are known as the ventral scales and the corresponding ones on the underside of the tail are called the sub-caudal scales, and are usually (but not always) in two rows. The row of scales along the centre of the back is called the vertebral row. These terms will be used in the descriptions which follow. The scales of the head are usually large and symmetrically arranged according to a definite plan. They lie side by side without overlapping. See Figs. 1-10.

The Elapid Snakes. Most of these are similar in general appearance to the harmless snakes of the great family Colubridae (to which belong over 75 per cent of Malayan land snakes) and no obvious feature distinguishes the Elapids apart from the large anterior poison fangs.

Common Cobra (Naja naja). The common Malayan variety of this snake is quite black with the belly bluish-grey and some white marks on the throat. In the northern states brown or ochreous coloured cobras are sometimes found. Its habit of raising the front of the body and spreading the skin on each side of the neck, the well known "hood", usually makes a living cobra immediately recognisable, but after death there is no sign of the hood at all.

If the head of a dead cobra is closely examined two scale characters will establish its identity. Firstly, the third from the front (not counting the front central one) of the scales bordering the upper lip is large and touches both the eye and the scale just behind the nostril; secondly, there is a small triangular scale on the margin of the mouth between the fourth and fifth lower lip-scales. These two characters are shown in Fig. 5. This snake grows to five or six feet in length.

Cobras will generally make for cover at the sound of a footstep and are not often trodden on accidentally. They are more alert and ready to bite at night than by day, and young ones are said to be more vicious than adults. The bite is dangerous and may be fatal, failing proper treatment, but is by no means invariably so. The cobra has the habit of spitting its venom, or rather blowing it out in a spray. If this enters the eyes it causes severe pain and may result in injury; do not closely inspect a cobra confined behind wire netting.

Cobras feed on almost any small animals that they can catch, and do good service by destroying rats.

King Cobra or Hamadryad (Naja hannah). The adult is brown or olive above, the scales dark-edged, especially on the tail and hind part of the body; throat yellow with black markings, conspicuous when the hood is spread; belly greyish-brown. When young this snake is dark brown or black with numerous narrow white or yellow cross-bars, chevron-shaped, their apexes pointing forwards; head black with four white cross-bars, two near the snout. one just behind the eyes and one further back; throat and belly white.


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The third upper lip-scale is like that of the Common Cobra and another scale character is diagnostic of this species. In most snakes the scales on the top of the head are large and symmetrically arranged, three lying between the eyes, a pair of large scales behind these and then the small scales of the neck. In the Hamadryad there is an extra pair of large scales between this group of five and the neck scales, a condition found in no other snake. This extra pair is shown stippled in Fig. 7. A further almost diagnostic feature is found on the under-side of the tail. In most snakes the scales on the tail, behind the anus (i.e. the subcaudal scales), are in two rows (Fig. 10), in a few they are all single like those of the belly. In the Hamadryad (and also in the Red-headed Krait) both single and paired subcaudal scales are present (Fig. 8). As this feature is shared only by one of the kraits it is, of itself, an indication of a poisonous snake.

The Hamadryad is the largest of all poisonous snakes and is known to exceed eighteen feet in length; thirteen to fifteen feet is the usual length of adults. It is often reputed to be aggressive and to attack habitually without provocation, but in fact it will practically never do this. It is, nevertheless, a dangerous animal and should never be trifled with; do not throw stones at a hamadryad or try to kill it with an inadequate stick. The bite of a large one is likely to be rapidly fatal.

So far as is known this species feeds entirely on other snakes and monitor lizards.

Banded Krait (Bungarus fasciatus). The entire length of the snake is marked with alternate black and pale yellow or almost white cross-bands, the black bands usually a little wider than the yellow interspaces and continued across the belly, thus encircling the body. The tip of the tail is blunt and the subcaudal scales are all single (Fig. 9). The bright black and yellow banding and the single subcaudals serve to distinguish this snake. It is often confused with the harmless Yellow-ringed Cat Snake, which is black with narrow yellow rings and has the subcaudals double. This is the largest of the kraits and may reach seven feet in length.

All accounts of this snake testify to its inoffensive disposition and reluctance to bite, and cases of people being bitten are extremely rare. Its venom is known to be less toxic than that of the cobra, nevertheless, if a bite should occur, it should be treated as a serious matter. All the kraits feed only on other snakes.

Malayan Krait (Bungarus candidus). Black above with about thirty white cross-bands on body and tail; these cross-bands widen on the flanks where they join the unrelieved white of the belly. Towards the front the black inters paces are much wider than the white bands, posteriorly and on the tail only slightly wider or equal. In the adult the white bands are speckled with brown, more heavily on the front part of the body. The tail tapers to a point and the subcaudals are all single as in the Banded Krait. The colour pattern and the single subcaudal scales distinguish this snake from any other Malayan species. The young of the harmless Banded Wolf Snake (Lycodon subcinctus) is similarly marked, but the white bands are relatively much narrower, and the subcaudal scales are in two rows (Fig. 10). The Malayan Krait grows to between three and four feet.


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Like all kraits this snake is reluctant to bite in self defence, but probably less so than the Banded Krait . Its bite is known to be dangerous to human life.

Red-headed Krait (Bungarus (laviceps). Body iridescent blue-black above with the head, tail and one or two inches of the hinder part of the body scarlet. In the young there is a bluish-white stripe low down on each side and a line or row of dots of this colour along the centre of the back. Belly white in adults, blackish in young snakes. Five to six feet is the usual length of adults. The subcaudal scales are partly single and partly double, as in the Hamadryad.

This spectacular snake is rather rare and is encountered most often in forest in foot-hill country. There is no record of anyone ever being bitten by one, but by analogy with the other members of the genus it is to be accounted dangerous. Its coloration is curiously similar to that of the next species to be described.

Blue Malaysian Coral Snake (Maticora bivirgata). Dark blue above with a pale blue stripe low down on each side; head, tail and belly bright coral red. This snake, which grows to about five feet, is similar in appearance to the Red-headed Krait, but can be distinguished by the red of the under surface. Other characters are afforded by the subcaudals (all double in Maticora) and the vertebral row of scales, which are enlarged in all the kraits and the same size as those alongside them in the coral snakes. M. bivirgata is common in forest and secondary jungle everywhere in the lowlands, including Singapore Island.

This species and the next, i.e. the genus Maticora, have the peculiarity that the poison glands, instead of being confined to the head, extend into the body for a third of its length. The Asiatic coral snakes are, however, very seldom known to bite people, in fact their mouths are so small that they are almost incapable of biting so large an object as a human hand or foot. We know of no recorded case of a bite by the present species. Like the kraits the coral snakes are snake-eaters.

Banded Malaysian Coral Snake (Maticora intestinalis). Brown and black above with a narrow red stripe along the middle of the back and a light coloured stripe low down on each side; the belly alternately barred black and white, the under-side of the tail barred black and bright red. Grows to about two feet in length and is common throughout Malaya.

One case is known of this snake biting a man. It implanted one fang only in the web of the skin between his fingers , and he was rather ill. A full dose of venom from both fangs of one of these snakes might well be a serious matter, but, as recorded in the description of M. bivirgata, they are almost incapable of biting a person.

Spotted Coral Snake (CaUophis gracilis). Brown above with a black line down the middle of the back and one on each side; round black spots are spaced along these lines like beads on a string, the vertebral ones alternating with those on the sides; some fine black and yellow lines low down on each


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side. Belly marked with black and white cross-bars, under-side of tail black a.o.d red, just as in Maticora intestinalis. Grows to about two feet and is uncommon in Malaya.

The coral snakes of the genus Callophis do not have the poison glands extending into the body. They are also practically incapable of biting a human hand or foot and nothing is known of the effect of their venom. It seems likely that they need not be accounted dangerous.

Small-spotted Coral Snake (Callophis maculiceps). Light brown above with a black vertebral stripe or small black spots along each side of the back; tail with two black rings, one at the base, the other near the tip; belly red, under-side of tail grey. Grows to a little over eighteen inches.

Very rare in Malaya and confined to the northern states.

The Vipers. This is a very distinct group of snakes, all venomous, which differ from the Elapids in having the poison fangs very long and attached to a short upper jaw-bone which is hinged to the skull, so that the fangs lie directed backwards when the mouth is closed and are erected when it is opened. The action of the venom is also very different from that of the Elapids. The head of a viper is always broad and flat and very distinct from the neck.

All the Malayan species belong to a group known as Pit Vipers, or Crotalinae which have a consipicuous pit on each side of the head, between eye and nostril. It has been shown that this is a thermo-sensitive organ, capable of detecting radiant heat in minute amounts, and probably used for locating warm-blooded prey.

Malayan Pit Viper (A ncistrodon rhodostoma). Reddish or purplish brown above with a series of 25 to 30 large, dark brown triangular spots on each side of the back, their apexes upwards, meeting or alternating along the vertebral line. Head broad, with a conspicuous pit between eye and nostril; dark brown above with a light pinkish-brown streak running from the snout backwards over the eye, a pinkish band along the upper lip, its upper margin scalloped. Poison fangs very long and enclosed in a fold of skin. Grows to between two and three feet.

This is a snake of the Asiatic mainland whose range extends into the north of the Malay Peninsula to about the latitude of Penang. In Kedah and Perlis it is common and cases of its bite are rather frequent .

Vipers of the genus Trimeresurus. These vipers can be recognised collectively by the presence of the pit between eye and nostril together with the condition of the scales on top of the head, which are small and irregularly arranged, more than 3 lying on a line between the eyes. Six species are found in Malaya; a key to distinguish them is given on p.116 of "The Snakes of Malaya". The three most common species are described below.

Wagler's Pit Viper (Trimeresurus waglen). The young and adult are very different, each having a distinct colour pattern. The former is green with regularly spaced spots each of which is partly white, partly red; the head has a white and red streak on each side at the level of the eye. The


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adult is black with scattered green spots above, passing to green, with the scales black-bordered, on the sides; this pattern crossed by numerous crossbars, green on the back, yellow on the sides; head black above with irregular green markings. This is a common snake in the lowlands and is sometimes found in mangrove swamp.

Shore Pit Viper (Trimeresurus purpureomaculatus). The colour is variable. Sometimes the snake is entirely dark purplish brown or blackish, there may be a white line low down on each side, or the body may be olive or greyish-brown with dark brown markings. This viper inhabits mangrove or other vegetation near the sea shore, and is particularly common on small islands lying off the coast.

Mountain Pit Viper (Trimeresurus monticola). Brown with a series of more or less square black spots along each side of the back, another series of smaller black spots below them; head black and brown with a whitish streak running back from the corners of the mouth. The scale immediately over each eye is larger than the other scales on top of the head. Wholly confined to the mountains, this snake is rather common at Cameron Higlands, Fraser's Hill and other high altitude localities.

All these vipers have rather similar habits. They live in low trees and bushes and feed on any small animals that they can catch. In general they are rather sluggish and reluctant to bite, especially by day, but cases are not infrequent as they are the commonest of our terrestrial poisonous snakes.

Sea Snakes (Hydrophiidae) . These can be distinguished from all other snakes by the shape of the tail , which is flattened like a fin or the blade of an oar. They live entirely in the sea and river mouths, most species frequenting shallow coastal waters. Only one, Pelamis platurus, is found far from shore and ranges widely in the Indo-Pacific ocean . This is a rather small brown and yellow snake, often seen from sea-going ships.

The Sea Snakes are divided into two subfamilies, the Laticaudinae and the Hydrophiinae. The former have the transverse scales of the belly (ventral scales, Figs. 2 and 3) well developed; in the latter they are rudimentary or absent. One of the Laticaudinae is commonly met with on small coastal islands, where it comes ashore to lay its eggs. This is the Amphibious Sea Snake (Laticauda colubrina), bluish-grey above with black cross bands, the head marked with black and yellow. It is extremely inoffensive and, although often handled, has never been known to bite. Nevertheless it is well equipped with poison fangs and glands and should be treated with respect. Do not kill these snakes when you encounter them, merely leave them alone.

The majority of the sea snakes belong to the Hydrophiinae. Discrimination of the species is a matter of some difficulty and no attempt will be made to provide for identification of them in this pamphlet. Collectively they can be distinguished by the flattened tail and extreme reduction or absence of the ventral scales. The commonest of them, Enhydrina schistosa, is uniform grey above, whitish beneath, when adult, and grows to three or four feet. The body is as thick as a man's wrist and similarly flattened. Some species of the genus Hydrophis are locally abundant, and are usually marked with light and


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dark transverse bands, as are several species of other genera. One sea snake, Hydrophis spiralis, reaches nine feet in length but is slender, and Astrotia stokesi, which is banded black and yellow, is very thick and massive. Most of the others are quite small slender snakes, rarely exceeding four feet.

The Hydropbiine sea snakes bear their young alive and fully developed for an independent existence, and are entirely aquatic, never coming to the land. They are, however, mainly confined to shallow water because they require to dive to the bottom to seek the eels and small fish which are their prey, and are often abundant in river mouths. They are not aggressive and do not bite readily, but must all be regarded as very dangerous. Fishermen, who catch them in their nets, are occasionally bitten, and there are cases of people wading in shallow water being bitten as a result of stepping on sea snakes. The open coast is quite safe for bathing and wading, but river mouths should be avoided, especially if there is a fishing village there. When wading in coastal waters, shuffle or slide your feet along the bottom instead of taking ordinary steps. This precaution is effective against the stinging fish, rays and Plotosid catfishes, as well as sea snakes.

The following KEY will provide in an empirical manner for the discrimination of a poisonous from a harmles~ snake in Malaya.

I Look at the tail; if it is flattened from side to side like a fin or the blade of an oar the snake is a Sea Snake and is poisonous.

If it is rounded or only very slightly flattened it may be poisonous or harmless. To decide:

II Turn the snake on its back; if the scales on the belly (ventral scales) are small like the rest of the body scales (Fig. 1), or extend only half way across the body (Fig. 2) the snake is harmless.

If the ventrals extend across the width of the body (Fig. 3) it may be poisonous or harmless. To. decide:

2 3 Ventral Scales


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HI Examine the top of the head; if the scales thereon are small and irregularly arranged, more than three lying 'On a line between the eyes (Fig. 4), and the subcaudal scales are all double (No. V below and Fig. 10), the snake is a Pit Viper of the genus Trimeresurus and poisonous.

If the scales on the head are large and symmetrically arranged, only three lying on a line between the eyes, it may be poisonous or harmless. To decide:

IV Examine the side of the head; if either (A) the third scale bordering the upper lip is large and touches both the eye and the scale immediately behind the nostril (Fig. 5) or (B) there is a deep pit between the eye and the nostril (Fig. 6), the snake is poisonous, being (A) a Cobra, Hamadryad or Coral Snake or (B) the Malayan Pit Viper. (See the foregoing text for additional diagnostic features of the Hamadryad and Common Cobra).

If none of these features is present, it may be harmless or poisonous. To decide:

~ 5

7 Head Scales


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9

V Examine the scales on the under side of the tail (subcaudal scales); if they are partly single and partly double (Fig. 8) the snake is a Red-headed Krait and poisonous. This feature is shared by only one other Malayan snake, the Hamadryad. If they are all single (Fig. 9) and the snake is conspicuously banded black and white or black and yellow, it is the Malayan or the Banded Krait and poisonous. If the subcaudals are all double (Fig. 10), the snake is harmless.

9 10 Subcaudal Scales

Any snake which is not indicated as poisonous by the Key and does not correspond with any of the descriptions of venomous snakes can be regarded as hannless.


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