Snakes & Poison Apparatus Dr. Jagdish Kaur P.G.G.C., Sector 11 Chandigarh

SNAKES … Ectothermic reptiles belong to the suborder Serpentes bears well formed biting apparatus coupled with toxic venoms, products by the poison gland In the world, there are about 3000 living species of snakes out of which 300 are poisonous In India nearly 325 species are present out of which 70 are poisonous, rest are non- poisonous.

A SNAKE HAS TWO HOLLOW TEETH {FANGS} A SNAKE HAS TWO HOLLOW TEETH {FANGS}. WHEN IT BITES, THE POISON ENTERS THE PERSONS BODY THROUGH THE FANGS

POISON APPARATUS IN SNAKES … Poison Glands … Poison glands - modified superior labial or parotid glands. situated on the either side of the upper jaw Sac-like structure thickly encapsulated with fibrous tissue narrow duct from the anterior end of the poison sacs and passes forward along the side of the upper jaw and loops over itself just in front of the fang. capsule supports vascular fibrous septa that separate the glandular substances into secretory pockets.

POISON APPARATUS IN SNAKES … Fangs … Fangs- Snakes eject venoms by their two hollow maxillary teeth called fangs Fangs are long sharply pointed and hook like, being extremely hard and calcified with a superficial enamel layer

POISON APPARATUS IN SNAKES … Fangs … Open type : furrowed by a groove for the conduction of the venom. Closed type : Fang becomes almost or totally tubular, hypodermic syringe like structure due to approximation of the groove tips. Opisthoglyphodont : fangs lie at the back of the maxilla and are of open category. Proteroglypodont : fangs are situated at the front end of the maxilla and are at closed category. According to the structural differences poison fangs According to the position, the poison fang may be

POISON APPARATUS IN SNAKES … Poison glands - modified superior labial or parotid glands. situated on the either side of the upper jaw Sac-like structure thickly encapsulated with fibrous tissue narrow duct from the anterior end of the poison sacs and passes forward along the side of the upper jaw and loops over itself just in front of the fang. capsule supports vascular fibrous septa that separate the glandular substances into secretory pockets.

POISON APPARATUS IN SNAKES … Muscles - Digastric muscle; sphenoterygoid; anterior and posterior temporalis

Mechanism of snake bite Opening of mouth by contraction of digastric muscle Rotation of maxilla bone Fangs become erect and press the victim Mouth closes by the action o temporalis muscles Injection of poison is completed

Snake venom … Highly complex chemical mixtures that “may contain many proteins, mainly particular enzymes, and strongly basic polypeptides The chemical compositions of venoms are known to vary intra-specifically for a number of reasons

Snake venom … The geographic variation in venom - closely related to diet and thus reasoned that natural selection had directed venom composition to make the venoms most effective against the specific prey types that snakes in separate areas would encounter As a general rule, venoms seem to be either highly toxic (to bring about rapid prey death) or highly proteolytic (presumably to help with chemical digestion)

Snake venom … Neurotoxic … Haemotoxic … produce paralysis and death by respiratory shock rich in basic amino acids act at the molecular level by disrupting neuromuscular junctions and hence limit muscle activity Low molecular weight – fast diffusion process have hemorrhagic effects often cause tissue destruction in other body systems - attributed to proteins and digestive enzymes such as phospholipase A2 Higher molecular weight – slow diffusion process Neurotoxic … Haemotoxic …

Features of poisonous & non-poisonous snakes Head - Triangle - except Cobra Fangs - Present Pupils - Elliptical pupil Anal Plate - Single row of plates Bite Mark - Fang Mark Non Poisonous Snakes Head - Rounded Fangs - Not present Pupils - Rounded Anal Plate - Double row of plates Bite Mark - Row of small teeth.

Poisonous Snakes Triangular shape of head Small head scales Colour is bright Hood is present Loreal pit is present between nostril and eyes Belly scales or ventrals are large and extend from side to side Indian Cobra

Poisonous Snakes COMMON KRAIT Maxilliary teeth are comparatively longer and have canal and called fangs Poison glands are present Poison glands are modified labial glands Tail is laterally compressed COMMON KRAIT

Non-Poisonous Snakes Elliptical shape of head Head scales are large Colour is dull Hood is absent Loreal pit is absent Belly scales are small and continuous with dorsals HOGNOSE SNAKE

Non-Poisonous Snakes All teeth are same Poison gland is absent Tail is cylindrical SCARLET KINGSNAKE GARTER SNAKE

Indian Cobra The Indian cobra (Naja naja) also known as the Spectacled cobra, Asian cobra. cobra is a species of the genus Naja and a member of the "big four" species that inflict the most snakebites  This snake is revered in Indian mythology and culture, and is often seen with snake charmers. It is now protected in India under the Indian Wildlife Protection Act (1972)

Common krait The main origin is shivalik hills of chandigarh. The average length is 0.9 m (3.0 ft), but they can grow to 1.75 m (5 ft 9 in). Males are longer, with proportionately longer tails. The head is flat and the neck hardly evident. The body is cylindrical, tapering towards the tail. The tail is short and rounded. The head shields are normal, with no loreals. Colouration is generally black or bluish black.

Look for the accentuated neck of a poisonous snakes Look at the shape of the snake's head. All but one of the venomous snakes in Georgia has a triangular shaped head. The base of the head is much broader than the tip. It almost looks like it has a neck. Non-poisonous, or non-venomous, snakes will have a rounded head without the obvious broad base. Their body will be virtually straight from tip to tail unless they are feeling threatened, then they will flatten their head.

Round eyes indicate a non-poisonous snake. Look at the snake's eyes. Non-venomous snakes have round, circular pupils. The venomous, or poisonous, snake will have elliptical pupils that look like a cat's eyes. Their eyes are oval, not round.

The pit on a poisonous snake is used to the detect body heat of potential prey. Look for a small pit between the snake's nose and eyes. All poisonous snakes in Georgia will have a heat-sensing pit on each side of the head. This pit is the origin of the term "pit-viper" sometimes used to describe a venomous snake. Non-poisonous snakes do not have these pits. The area between the nostril and eye will be smooth.

Poisonous snakes look fat and thick in the middle. Observe the shape of the snake's body. Most non-poisonous snakes will have slender bodies. The poisonous snake's body is wide and thick. Do not confuse length with thickness. Snakes of either variety can range from a few inches to several feet in length.

Leaning skin pattern is an easy method for identifying poisonous snakes. Look for a skin pattern. The characteristics listed in the steps above are distinctive for the two types of snakes, but skin pattern is not. While most non-venomous snakes have only a minimal pattern, there are some that have variations in colors and stripes. The venomous snakes, on the other hand, will each have its own distinctive pattern of stripes or color splotches. Learn the skin pattern of each poisonous snake if you frequent areas that may be home to snakes.