Pit Viper

Certain group of snakes do what no other animal or artificial device can do.They form detailed image of extremely small heat signatures,what is most fascinating is that they do this with receptor that are microscopic in size,extraordinarily sensitive,uncooled and are able to repair themselves.

Snakes infra-red imagers are at least 10 times more sensitive than the best artificial infra-red sensor

pit organ afferent  demonstrates that receptors are sensitive to very  small  temperature  changes ( ~0.003 deg Celsius).

HOW DOES THE SNAKE See ?

The detection systems,which consist of cavities located on each side of the head called pit.

The detection system consist of cavities located on each side of head called pit organs,operated on principle similar to that of pinhole camera.Pit viper and boids the tow snake that possess this ability,have heat -sensitive membranes that can detect the difference in temperature between a moving prey and its surrounding on scale of mK.IF the radiation intensity hitting the membrane itself,membrane heats up that location.The picture of such cavities is presented in fig below.

Fi

Figure 1.: Snake heat vision : a)Head of pit viper with nostril,pit hole and eye,left to right

.b) A pit vipers infra-red sensitive pit organ works like a pinhole camera.

According to the Planck radiation law as an approximation of the emitted heat intensity,99% of the radiation is emitted at wavelengths under 75 micrometers and the radiation intensity is maximal at 9.5 micrometers which is within the 8-12 micrometers IR atmospheric transmittance window.

Because the pit hole is very large compared to the membrane size,the radiation strikes many points.Optical quality of the infra-res vision is much too blurry to allow snakes to strike prey with the observed accuracy of about 5 degrees.The most fascinating is an amount of heat-sensitive sensors and their precision.

In Pit vipers,which have only two pit holes ( One in front of each eye ), a block of about 1600 sensory cells lie on membrane which has field of view of about 100 degree.This means the snake's brain would receive an image resolution of about 2.5 degrees for point -like objects,such as eyes,which are one of the hottest points on mammals.

If the aperture was very small,the amount of energy per unit time (second) reaching the membrane would also be small.The need together a reasonable amount  of thermal energy per second necessitates the " Pin Hole " of the pit organ to be very large,thus greatly reducing its optical performance.If on the other to be very large,thus greatly reducing its optical performance .If on the other hand the aperture of the organ is large,the image of a point source of heat is disc-shaped rather than point-like.

Since ,however ,the size of disc-shaped image may be determined by the detectors on the membrane,it is still  possible to tell from which direction the radiation comes ,ensuring directional sensitivity of the system. The aperture size was probably  an evolutionary trade off between image sharpness and radiant flux.Although image that us formed of the pit membrane ha very low quality the information that is needed to reconstruct the original temperature  distribution in space is still available.

So how a snake could possible use such poorly focused IR input to find its prey in darkness with a surprising angular precision of 5 degrees ?How the snake may be able to extract information on the location of the prey from the blurred image that is formed on the Pit-membrane.

WHAT DOES THE SNAKE SEE ?

Without the ability of real time imaging the IR organ would be of little use for the snake.so Dr.Van Hemmen proved that it is possible to reconstruct the original heat distribution using the blurred image on the membrane.

The image on the membrane resulting from the total heat distribution in space will be  some complicated shape that consist of the superposition of the contribution of all heat sources.A superposition of edge detector in the brain can now reconstruct the heat distribution by using the whole image on the membrane for each point in space to be reconstructed so reconstruction is possible because the information is still available in th blurred image on the pit membrane,where the receptor are. As a demonstration of the model image was used

Figure -2: The Famous hare by Durer ( left ) was coverted into 8-bit gray at a resolution of 32X32 (right).
Since a snake has limited computational resources ( all " Calculations"must be realizable in neuronal ' 'Hardware ' ') the reconstruction model must be simple.Our Model thus uses only one computational step ( it is non iterative) to estimate the input image from the measured response on the pit membrane.It resembles a wiener filter and is akin to,but different from,some of the algorithms used in image reconstruction.
So it is highly remarkable that snakes can perform some kind of an image processing like our artificial devices based on " wave front coding" and ' ' Pupil engineering techniques.

IMAGE PROCESSING IN NATURE
There was developed a neuronal algorithm that accurately reconstructed the heat image from the membrane.The Most vital requirements is accurate detectors and the ability to detect edges in the images produced on the pit membrane,.That is similar to the situation   with " wave front coding " device :The dynamic range and accuracy of the ADC is much more important that it is much more important than an amount of elements.

I would like to introduce an analogy here: such imaging like drawing a picture on a sand.The more fine the sand ,the more accurate and delicate pictures one can draw.That is the case of high dynamic range of the detector.And vice cersa: on a coarse and stony sand it is difficult to draw a fine tracery that is the case of low dynamic ranges detector.

But let us get back to the model of snake vision:
The model has a fairly high noise tolerance.For input noise levels up to 50%,the hare is recognizable  Sensitivity  to measurement errors corresponds to about 3 degrees.For detector noise levels up to about 1% of the membrane heat intensity,a good reconstruction is about one pixel accuracy.At detector noise levels beyond about 1% of the membrane heat intensity, a good reconstruction is about one pixel accuracy .At detector noise levels beyond about 1% the image is not so easily recognizable,but the presence of an object is still evident.
The assumptions that went into the calculations are a "worst case scenario".For instance,we assumed that the input to the pit organ is totally uncorrelated, meaning that the snake has no idea what heat distribution to expect.In reality,important information about the environment is always available.For example,typical temperature and size of aprey animal may be encoded in th neuronal processing structure.If the snake " know"what kind of images to expect,the reconstruction process can be enhanced considerably.

How does the reconstruction matrix become imprinted on the snake's neural circuitry in the first place? ``It can't be genetic coding,'' says van Hemmen. ``The snake would need a suitcase full of genes to encode such detail. Besides we know that snakes ...need a season of actual learning, not just anatomical maturation, to acquire their extraordinary skills.''... [11]

On the Fig. 3 it is shown a deconvolution results that give us a concept of the snakes vision capabilities.

Figure 3: On the left, this figure displays the membrane heat intensity as captured by the ``pithole camera''. On the right are reconstructions for four different membrane noise levels. The pit membrane was taken as a flat square containing41x41 receptors. The model works equally well if applied to other membrane shapes. The membrane noise term was taken to be Gaussian with SIGMA= 25, 100, 200, and 500 from left to right and top to bottom, corresponding to 0.25%, 1%, 2%, and 5% of the maximal membrane intensity. The image from the paper [2]

Ultimately, a snake's ability to utilize information from the pit organs depends on its capability to detect edges in the image produced on the pit membrane. If the snake performed no reconstruction, but instead simply targeted bloblike ``hot spots'' on the membrane, it would still have to be able to discern the edge of the blob. The present model performs edge detection for all spatial positions and hence automatically creates a full reconstruction. A level of neuronal processing beyond what is represented in our model is unlikely to be beneficial since the quality of the system is fundamentally limited by the relatively small number of heat receptors.[5]

Conclusion

Snakes' heat vision presents such a clear image when reconstructed that it surpasses even many human devices - it is far better than any technical uncooled infra-red camera with a similar number of detector cells [2].

Russel Viper

Common Name :- Russel Viper

Venom/Non Venom :- Highly Venomous Snake.Third most common venomous species.

Local Name/Marathi Name: -घोनस
Distribution : - All over India ,Not found in North east and Kashmir.
Status :- Common, Most Common Viper in India. 
Average Length:- 100 cm ( 3 feet 3 inch)
Maximum Length:- 180 cm ( 5 feet 11 inch )
Breeding Season:- In Between May to July or Mid August Female give birth to 6-63 live young ( Generally not more than 60 ).
Venom type :- Hemotoxic Venom.

Description


Habitat.
Its not restricted to any particular habitat,but does tend to avoid dense forests.The snake is mostly found in open,grassy or bushy areas,but may also be found in second growth forest( scrub jungles) ,on forested plantations and farmlands. They are most common in plains,coastal lowlands and hills of suitable habitat. Genrally not found at altitude,but has been reported as far up as 2300-3000m. Humid envornment ,such as marches,swamps, and rain forests are avoided.
This species is often found in highly urbanized areas and settlements in the countryside,the attraction being the rodents comensal with man.As a result,those working outside in these areas are most at risk of being bitten.


Behavior
Russell Viper is a nocturnal Species like other Vipers;but can be sighted in scrubs and bushes during day time for basking,during winter it can stay at single place for more than one day for mating and basking.Lives in bushes,scrubs,rocks,dense vegetation,agricultural lands,dry leaves,grass lands,wood piles etc.

Behavior very agile and uncertain on provocation;
First Produce whistle sound ( Like pressure cooker ) as warning sign,will coil its body with head at center of the coil and may attack anytime on further disturbance.Can bite even when its body is elongated while creeping.
Not a very good climber and like to remain on ground for better adjustment with its surroundings.Vary rarely ,if conditions and adverse,it may climb up to a certain height.Once a sub adult was found on hut in the month of December in MP
Feeds on rodents,birds,lizards adn small mammals,No genuine record of cannibalism from this species.
This snake is terrestrial and active primarily as nocturnal forager.However,during cool weather it will alter its behavior and become more active the day.
Adults are reported to persistently slow and sluggish unless pushed beyond a certain limit,after which they become aggressive.Juveniles,on the other hand,are generaaly more nervous.
When threatened they form series of S-loop,raise the first third of the body and produce a hiss that is supposedly louder that that of any other snake.
When striking from this position,they can exert so much force that even a large individual can lift most of its body off the ground in the process.These snakes are strong and may react violently to being picked up.The bite may be snap or they may hang on for many seconds.
Although this genus doesn't have the heat-sensitive pit organs common to the ceotalinae,it is one of a number of viperines that are apparently able to react to thermal cues,further supporting the notion that they too possess a heat-sensitive organ.The identity of this sensor is not certain,but the nerve ending in the supranasal sac of these snakes resemble those found in other heat-sensitive organs

Territory

Feeding Habits ( Food )

Distinctive Feature

Breeding,Housing and Nesting

General Size and Shape

Breeding Season ( Reproduction )

Egg

Importance of Snake

Survival,threats and Danger

Mimicry

Prey

Venom

Symptoms after Bite

Snakes Find In India

As you know Snakes are divided into two types poisonous and non poisonous. By family snakes, fishes, lizards, crododiles, dinosars and birds belong to same group.

Of the over 2000 species of snakes in the world, about 200 are found in India. These range from the worm snakes having a length of about 10 cms. to those more than 6 mts. long. They live in almost all habitats from the warm seas to semi-deserts, swamps, lakes and even in the Himalayan glaciers up to an elevation of about 5000 mts. Thirty main species of Indian snakes have been discribed here. 

Common Worm Snake
( Typhlina bramina): A small worm-like snake found all over India. In the hills, it lives up to an elevation of 1000 mts. 

Perrotet's Shield-tail Snake
(Plectrurus perroteti): A small snake found in the hills along the west coast of India, i.e., The Western Ghats, Nilgiri and Annamalai hills. 

Indian Rock Python
(Python molurus): A large thick-bodied snake found in many parts of India. It ranges from the mangrove forest to arid scrublands and dense rain forest of the eastern Himalayas up to an elevation of about 2000 mts. 

Common Sand Boa
(Eryx conicus): A short thick-bodied snake found in the plains and low hills of India. They are nocturnal and hunt after dark. 

Red Sand Boa
(Eryx johnii): A medium-sized snake with a very blunt tail. It is found in the drier tracts of the country. 

Common Wolf Snake
(Lycodon aulicus): A small slender snake found throughout India. In the hills, it occurs at an elevation of about 2000 mts. 

Banded Kukri 
(Oligodon arnesis): A small snake with prominent cross bands on its body. Found all over India and up to an elevation of 200 mts. in the eastern Himalayan. 

Stripped Keelback 
(Amaphiesma stalata): A small to medium-sized snake that is closely related to and resembles the water snake. Found all over India and up to an elevation of 2000 mts. in the hill. 

Green Keelback 
(Macropisthodon plumbicolor): A medium-sized keelscaled snake found in the forested region of India up to an elevation of 1500 mts. 

Checkered Keelback Watersnake
(Xenochropis piscator): A medium-sized keeled snake found all over India up to an elevation of about 3000 mts. 

Olive Keelback Watersnake
(Altritium schistosum): A small to medium-sized snake found in central and peninsular India up to an elevation about 1000 mts. 

Trinket Snake 
(Elaphe halena): A medium-sized, slender snake found all over India up to an elevation of about 4000 mts. in the Himalayas. 

Rat Snake 
(Ptyas muscosus): A large-scaled snake found all over India up to an elevation of about 4000 mts. It is capable of adapting to almost any environment. They are prodigal rat-eaters. 

Banded Racer
(Argyrogena fasicolatus): A small to medium-sized snake found in the plains of India. It prefers to live amongst tall grass and bushes. 

Royal Snake 
(Spalerosophis diadema): A medium to large-sized snake found in the drier tracts of Rajasthan, Punjab, Haryana, Uttar Pradesh, Jammu hills and Himachal Pradesh up to an elevation of 2000 mts. 

Bronze-back Tree Snake
(Dendrelaphis tristis): A medium-sized slender snake found all over India up to an elevation of 2000 mts. in the Himalayas. They prefer low bushes and thorny trees. 

Flying Snake
(Chrysopelea ornata): A small to medium-sized snake found in the forest of southwest India and northeastern parts of the country north of Bihar and Orissa. They prefer to live on large trees and appear to glide for some distance. 

Vine Snake
(Ahaetulla nasutus): A medium to large-sized snake found all over India, except in the northwest and parts of the Ganga plain. They may occur at elevation of about 2500 mts. preferring low bushes and trees. 

Common Cat Snake
(Boiga trigonata): A small to medium-sized snake found all over India up to an elevation of 3000 mts. in the Himalayas. They are nocturnal in habit and prefer to spend the daylight hours in a cool place. 

Dog-faced Watersnake
(Cerberus rhynchops): A medium-sized snake found in the coastal tracts. They live in muddy and rocky areas in estuaries, mangrove swamps, salt pans and deserted creeks. 

Common Krait
(Bungarus caeruleus): A medium-sized snake with thin white bands on its body. Found almost all over India up to elevation of about 1700 mts. They are nocturnal in habit. 

Banded Krait
(Bungarus caeruleus): A medium to large-sized snake with prominent yellow and black bands on its body. Found in northeast India, Bihar, Orissa, Madhya Pradesh, Andhra Pradesh and Uttar Pradesh up to an elevation of 1500 mts. 

Sleder Coral Snake
(Callophis melanurus): A small slender snake found in most parts of the country except parts of central and northeast India, Bihar, Orissa, Madhya pradesh, Andhra Pradesh and Uttar Pradseh up to an Elevation of 1500 mts. 

Indian Spectacled Cobra
(Naja naja naja): A medium to large-sized snake found all over India up to an elevation of about 4000 mts. in the Himalayas. They feed on frogs, toads, rodents, birds and small snakes. 

Indian Monocled Cobra
(Naja naja kaouthia): A medium-sized snake found in northeast India, parts of Uttar Pradesh , Bihar, Orissa and West Bengal. They are mainly nocturnal in habit. 

King Cobra
(Ophiophagus hannah): A large-sized snake that may be up to 5 mts. in length . It has distinct cross bands on its forebody. Found in dense forests of South India, Himalayan foothills up to an elevation of 2000 mts., Orissa , Bihar, West Bengal and North east India. 

Hook-nosed Sea Snake
(Enhydrina schistosa): A medium-sized snake with a flattened body and tail. Found along the coast and coastal islands. They are seasonally found in the deep sea though they prefer coastal areas. 

Russell's Viper
(Vipera russellii) : A medium to large-sized snake with a characteristic bright pattern on its body. Found all over India, both in the plains and hills up to an elevation of about 3000 mts. 

Saw-scaled Viper
(Echis carinatus): A small-sized snake found all over India, usually in the plains. They may occur in areas as high as 2000 mts. in the northwestern Himalayas. 

Bamboo Pit Viper
(Trmeresurus gramineus): A small-sized snake with a triangular head. Found in the hills of central and eastern India. It prefers cold, thick vegetation along watercourses and bamboos and other dense foliage. 

Some Other Common Snakes Of India
1. Slender Worm Snake (Typhilina porrectus) 2. Pied-belly Shield-tail Snake (Melanophidium punctatum) 3. Nilgiri Shield-tail Snake(Uropeltis ocellatus) 4.Regal Python (Python reticulatus) 5. Khasi Earth Snake (Stoliczkaia khasiensis) 6. Olive Forest Snake (Rhabdops olivaceus) 7. Glossy Marsh Snake (Gerarda prevostiana). 

POISONOUS SNAKES OF INDIA:

Indian (Spectacled) Cobra - Naja naja naja

Distinctive Features: Medium-sized to large; smooth, shiny scales; wide head and neck; wide black band on underside of neck; distinctive hood marking on top of neck.

Description: The Spectacled Cobra is a smooth-scaled snake with black eyes, wide neck and head and medium body. Colouring varies form black or dark brown to yellowish white. The underside is usually white or yellowish with a wide dark neck band. The body is generally covered with a speckled white or yellow pattern, sometimes forming ragged bands. The famous hood marking of the classic design, shows a connected pair of rings. Occasionally, it may not even resemble spectacles, or may be altogether absent. The cobras of northwest India are blackish and have a barely distinguishable hood marking. Cobras are often confused with the Indian rat snakes, which have a much thinner neck and head, and become 3 metres long, a metre more than do the biggest Indian cobras.

The Spectacled Cobra is the most widely distributed of the generally accepted 3 sub -species of cobras in Indian and is one of the big four dangerous snakes, 6 species of cobras occur in Asia and 9 in Africa. The jet black cobras occur in Asia and 9 in Africa. The jet black cobra of northwest India and Pakistan is another sub-species or geographic race. Except for its colour and absence of hood marking, it is very similar to the spectacled Cobra.

Distribution: Throughout India, sea level upto 4000 m (in the Himalayas)


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King Cobra - Ophiophagus Hannah

Distinctive Features: Large; smooth, shiny scales; distinct light cross bands mainly on the forebody; large head scales edges with black.

Description: The large head of the giant King Cobra is little wider than the neck. The head scales are edged with black and the overall colour varies from yellowish to deep olive-green but the tail if often jet-black. The underside is a lighter shade of the body colour. The yellow bands on the snake's back are more obvious in the light coloured specimens from Orissa and Uttar Pradesh. King Cobras are the largest venomous snakes in the world.

Distribution: Rare in India, King Cobras are confined mostly to the dense forests of the Western Ghats and the northern hill forests. Nilgiris, Plains and Western Ghats upto Goa, the Himalayan foot hills (upto 2000 m) starting near Lahore in Pakistan through North Indian to Assam. Forests of Orissa, Bihar, West Bengal and the Andamans.


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Banded Krait - Bungarus fasciatus

Distinctive Features: Medium-sized to large; smooth, shiny scales: wide bright yellow and black bands on back.

Description: The Banded Krait is a large, conspicuous yellow and black banded snake with a prominent backbone, blunt tail and rounded head slightly distinct from the body. The bands are faded on the underside.

Distribution: Assam, Bengal, Bihar, Orissa and reported in parts of Madhya Pradesh, Andhra Pradesh and Uttar Pradesh. Found upto 1500 m above sea level.


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Slender Coral Snake - Callophis melanurus

Distinctive Features: small, slender; smooth, shiny scales: blunt, black head; tail black, scarlet and blue.

Description: The Slender Coral Snake is light brown and family speckled. The head and neck are black with two conspicuous yellow spots on the top of the head. There is a ragged black ring at the tail-base and at the tail-up. The underside is uniform pinkish-red (coral), bright scarlet at vent, and the underside of the tail is bluish. The head is blunt and has the same width as the neck; the scales are smooth and slightly glossy. Slender Coral Snakes are one of the 5 Indian coral snakes. The other 4 are hill forest species of the Western Ghats and eastern Himalayas.

Distribution: Reported from the most parts of India on the plains, except central and northwestern India. MacClelland's Coral Snake is found up to 4000 m in the Himalayas.


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The Indian (Monocled) Cobra - Naja naja kaouthia

Distinctive Features: Medium-sized; smooth, shiny scales; wide head and neck; distinctive hood marking different from that of the spectacled cobra.

Description: The skin of the Monocled Cobra is shinier, the hood rounder and smaller and the head smaller than is that of the spectacled cobra. The colour varies widely, from yellowish to greenish brown to black, with ragged bands. There is a conspicuous white monocle on the hood. The underside is yellowish white Monocled Cobras superficially resemble Spectacled Cobras, but there are many small differences.

Distribution: Monocled Cobras are a sub-species most commonly found in northwest India, parts of Uttar Pradesh, Bihar, Orissa and the Andamans, all of Bengal and Assam.


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Russells Viper - Vipera russellii

Distinctive Features: Medium-sized to large; strongly keeled scales; distinctive bright chain pattern; large triangular head.

Description: Russells Vipers are heavy, rough-scaled snakes with vertical eye pupils and generally a very bright pattern. The body colour is usually brown or yellowish and the pattern is composed of dark, round spots edged with white and black. The underside is white in the western, partly speckled in the southeastern and heavily speckled in the northeastern race. Colour variation is common, and the best recognition characters are the short, fat body, the triangular-shaped head and very regular chain like pattern. Russells vipers resemble the fat, harmless common sand boas which however have shorter and blunter tails and irregular body patterns. The bright symmetrical spots on Russells Viper's backs make them easy to differentiate. Russells Vipers are one of the big Four dangerous snakes of India. The other large Indian viper is the Levantine Viper, a heavy brown snake found in parts of Kashmir which grows to 11/2 m.

Distribution: Hills and plains throughout India upto 3,000 m.


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Saw-Scaled Viper - Echis carinatus

Distinctive Features: small; strongly keeled scales; head wider than neck; dull colour; cross mark on top f head distinctive.

Description: A rough scaled snake with large eyes, wider head than neck and stocky body. The scales are heavily keeled. The body is brown, grayish or sandy with a darker zigzag pattern on the back and a distinct cross or lance mark on the head. The underside is white with brown speckles. The tail is short and stubby. Saw-scaled Vipers are the smallest of the Big Four venomous snakes and are less of the threat to man in South India because of the small size of the southern type. The northern for, however, grows large enough to be a potentially dangerous member of the Big four.

Distribution: Throughout India, mostly on the plains. In northwest India, Saw-scaled Vipers are reported from upto 2000m ion the hills. They are plentiful in certain area such as Ratnagiri District in Maharashtra, parts of Punjab, Rajasthan, Tamil Nadir and Andhra Pradesh.


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Common Krait - Bungarus caeruleus

Distinctive Features: Medium-sized; smooth, glossy scales; head slightly wider than neck: jet-black, usually with distinct white cross lines.

Description: Common Kraits are smooth, glossy bluish-black snakes with the rounded head slightly distinct from the neck. The body colour varies from a dark steely blue-black in a specimen which has freshly shed its skin to a pale faded bluish grey in one just about to shed. There are normally about 40 thin white cross bands. The young and some adults may have white spots along the first third of the backbone in place of the cross lines. This variation as well as uniform black variants appear in certain geographic races. The underside is white. Common Kraits are often confused with wolf snakes (Lycodon sp.) which are much smaller, with flat, somewhat pointed heads. The Common Krait is the best known of the 6 Krait species found in India and one of the big Four dangerous snakes. Besides the Common and Banded Krait, the other krait are rare and confined to the eastern Himalayas and Assam.

Distribution: Most of India including the Andaman and Nicobar Islands: sea level up to 1700 m. uncommon in Bengal, Assam and Orissa, where the Banded Krait is found 

In India there is no spitting cobras found luckily