General Information About Snakes

Defining Snakes : What makes a snake different from amphisbaenians and lizards? This is not quite such a ridiculous question as it may seem . In fact , it is not too easy to come up with a definition that includes all the snakes but excludes other members of the Squamata . Firstly , snakes have no legs - but neither do some lizards nor any of the amphisbaenians . Snakes have no external ear opennings - again , neither do some lizards nor any amphisbaenians . We can however use a combination of characteristics that will get pretty close to defining snakes . All snakes have a backbone (They are vertebrates) but lack limbs , eyelids and external ear openings . In addition , snakes have a specialized row of scales along the underside of their bodies , the ventrals , whereas lizards have various patterns of scales but never a single row . The scales of amphisbaenians are peculiar in that they are arranged in rings around the body , so that small species superficially resemble earthworms . On the question of legs , even those lizards that have lost their legs retain vestiges of the limb girdles , as do the amphisbaenians , whereas , although some families of snakes do retain vestigal pelvic gridles none of them have pectoral girdles . Finally snakes have unique skulls - the bones of their upper jaws are not united at the snout but are free to move away from one another , so allowing the passage of larger prey items than would otherwise be the case . This arrangement is not found in lizards or amphisbaenians . In the hand , snakes are supple and muscular whereas legless lizards tend to be more rigid.


Is It A Snake? : Snakes are long , slender vertebrates without legs . This definition is not enough to separate snakes from some other groups of animals , through . Eels , for instance , are also long and slender and have no legs , but their scales are very small and they breathe through gills , which can plainly be seen just behind the head . It is not o easy to separate legless lizards and amphisbaenians , from snakes . All are reptiles , their bodies are covered with scales and they all breathe through lungs . We make a table to show you how to separate snakes from other legless lizards .

Snake , Lizard Or Amphisbaenian?

1a.Animal has four legs.......................Lizards
1b.Animal has no legs.........................Go To 2a
2a.Scales arranged in rings around body.......Amphisbaenian
2b.Scales overlapping and tile-like...........Go To 3a
3a.Eyelids present............................Legless Lizards
3b.Eyelids absent.............................Go To 4a
4a.Single row of wide ventral scales..........Snake
4b.Several row of small ventral scales........Legless Lizards



Natural History Of Snakes And Evolution Of Reptiles : Snakes are reptiles and branch of zoology that deals with this class of animals is known as 'Herpetology' . The word herpetology is derived from the Greek word herpeton , which means 'a creeping thing' . In the early days of zoology all lowly animals such as amphibians and reptiles were lumped together in this group of 'creeping things' and the word 'herpetology' was coined to encompass all of them .
The reptiles form a class of vertebrate animals intermediate between the fishes and amphibians on one hand and the higher vertebrates (the birds and the mammals) on the other . Modern reptiles include the crocodilians , the turtles , the lizards , the amphisbaenians , and the snakes - not forgetting the lizard like Tuatura , a single species that has an order all to itself . Snakes , lizards , and amphisbaenians are closly related and belong to a single order , squamata , with three suborders . The ancestors of our modern snakes and lizards appeared along with the first dinosaurs during the late Triassic period , almost 200 million years ago , although fossil records of these reptiles are sparse . The modern lizards (suborder Lacertilia) are likely to have branched off from the primitive order Eosuchia during the Triassic period , but the oldest definite fossil links between modern lizards and their ancestors originated in the Upper Jurassic period , about 140 million years ago . During the same period , the first bird ancestors arose . It is generally accepted that modern snakes (Suborder Serpentes) arose from the lizards in the early Cretaceous period , about 130 million years ago , but there is no hard and fast fossil evidence to link the two suborders .
Unfortunately , small lizards and snakes do not make good fossils , as the small , delicate bones tend to break down or become scattered .
Paleontologists (people who study fossils) are continually finding various bones , but without the other parts to go with them their task is extremely difficult . One can compare the paleontologists task to the hardest of jigsaw puzzles , with many of the key pieces missing . Due to this incomplete fossil evidence , snake evolution is based largely on theory . The earliest known fossil creatures resembling snakes are from the lower Cretaceous period some 130 million years ago . These were short and heavy and had a mixture of lizard and snake characteristics . Unfortunately , there is no intermediary evidence to link these creatures with modern snakes .
One of the most widely accepted theories is that all snakes evolved from burrowing lizards . Certain primitive lizards would have taken to burrowing into the substrate in order to escape from predators and perhaps to hunt other subterranean creatures (as some modern species still do) . This subterranean existence , over countless generations , would mean that certain modifications to the body would be necessary for the animal to remain successfull . In the dark , subterranean world , eyes were of little use , so they gradually became absorbed until only vestiges remained , these being just suitable for detecting the difference the difference between light and darkness . The method of burrowing meant that limbs also became dispensable , and all snakes have lost their external limbs (although some have retained limb girdles) . External ear openings would have also been an encumbrance in a subterranean environment , so these were also lost . At a further stage of their evolution , some of these burrowing creatures found it convenient to return to the surface . In a lighter situation , eyes again became important so they were redeveloped (although the eyelids were completely lost , the eyes being under a transparent protective scale called a brille) .
The limbs were almost completely or completely lost , so the reptile developed a serpentine method of locomotion . External ear openings were also lost , but modern snakes have developed an efficient mechanism for detecting vibrations through solid surfaces . Additional adaptations that probably developed during the burrowing period include a sophisticated method of scenting odors and a very highly developed sense of touch . Most modern snakes still have these attributes . In spite of the theory regarding the evolution of snakes from burrowing lizards , there is no modern lizard family that could be construed to be a link between lizards and snakes . Even the legless amphisbaenians (suborder Amphisbaenia) , which were at one time thought to be lizards 'turning into snakes' , have now been classified into their own suborder . Although they have some characteristics similar to some found in both lizards and snakes , they have further unique characteristics that suggest separate evolution . If the burrowing theory is true , it can only be proved if and when complete fossils of the intermediate forms are found .


Modern Snake Classification : The snakes living today , then , owe their existence to a rather complicated history of evolution , speciation and extinction going back over 100million years .During that time , the shape of the land has changed out of all recognition . The present distribution of the surviving families is dependent , to some extent , on the time at which they evolved ; old families tend to have a world-wide distribution whereas newer families have often failed to reach parts of the world that became isolated as a result of the breaking up of the landmass , a process that had already begun when they first put in an appearance and continues to this day . The classification of surviving snakes , though strongly linked to , and dependent upon , strongly linked to , and dependent upon , their evolution , is somewhat easier than that of extinct snakes . It is not straightforward , however , because many species are imperfectly known whereas others seem to have conflicting characteristics , making it difficult to assign them to one family or another . Again , different degrees of importance are assigned to various characteristics by different researchers . Many arrangements have therefore been put forward over the years , some of them differing only slightly from previous classifications while othrs are more revolutionary .
There are generally accepted to be 14 or 15 families of snakes but the 2400 species are by no means equally divided between them . Two families contain only one species each , one contains two species while another contains three . The largest family of snakes is The Colubridae , which has no accepted common name , has , at present , over 1500 species assigned to it . This family is most certainly derived from a number of ancestral lines and future research will undoubtedly divide it into a number of smaller families . At present , it is divided into subfamilies , some of which are better defined than others . For details please visit our SPECIES section .


Blind Snakes And Thread Snakes (Anomalepididae , Typhlopidae And Leptotyphlopidae) are small burrowing snakes , rarely seen on the surface . They are restricted to warmer tropical and subtropical regions .
File Snakes (Acrochordidae) are completely aquatic species that are found in fresh and marine waters in Asia and Australia .
Sunbeam Snakes (Xenopeltidae) are Asian species with smooth , highly iridescent scales .
Mexican Burrowing Snake (Loxocemidae) is the only member of its family and comes from Central America .
South American Pipe Snake (Aniliidae) is the only member of its family and is found in northern South America .
Shield-tailed Snakes And Asian Pipe Snakes (Uropeltidae) are found in India and Sri Lanka . They are secretive , burrowing snakes whose natural history is not well know .
Wood Snakes Or West Indian Dwarf Boas (Tropidophiidae) are found in the West Indies , with a few species in Central and South America .
Round Island Boas (Bolyeriidae) are found only on Round Island in the Indian Ocean . There is one surviving species and one other that is probably extinct .
Boas And Pythons (Boidae) are sometimes regarded as two separate families . They are found in most of the warmer parts of the world and include many small to medium sized snakes as well as know Giant Species .
Typical Harmless And Back-Fanged Snakes (Colubridae) include three-fifths of all snakes . They are found throughout the world except for the coldest regions and a few small islands . There is great variation in their shapes and sizes and some species are venomous.
Burrowing Asps (Atractaspidae) are poorly known burrowing snakes, some of which are venomous. They are found in Africa and The Middle East .
Cobras, Mambas, Kraits, Coral Snakes And Sea Snakes (Elapidae) are all venomous snakes. They are found in most of the warmer parts of the world except Europe and Madagascar.
Vipers And Pit Vipers (Viperidae) are venomous snakes with long, hinged fangs. They are found in most parts of the world except Australia and Madagascar.



Size , Shape And Colour : The size and the shape of a snake together with the colour and markings , help to give each snake its identity . They may also hold important clues to the lifestyle of the snake because certain habitats and conditions tend to limit or encourage the wy in which snakes evolve. World's longest snake is The Reticulated Python (33ft, 10meters) and World's largest snake is Green Anaconda (18.9m Anaconda reported in Brazil 1907). Being large confers a number of advantages, not least the ability to avoid predation and to eat a wider variety of prey. At the same time, large snakes need to eat more than small ones. Even though snakes can survive on remarkably small amounts of food, finding enough prey to keep a 130kg (300lbs) body and soul together is no easy task, especially for an animal that is not very mobile and must, to a great extent , sit and wait for its meals to come blundering by. Large snakes, then, must live in areas where suitable food is relatively abundant.
In addition, their large bodies take longer to warm up than small ones and being cold-blooded, they cannot become active unless their body temperature is raised to a suitable level. For this reason, they are restricted to warm parts of the world. In practice, the regions where both these requirements are met fall within the tropics. Here, the ambient temperature is suitable and there is a reasonable chance of finding food every few days.
Just as snakes vary in size, so they vary in shape. Compared to most other animals, all are long and thin of course , but some are longer and thinner than the others. There is some degree of correlation with habitat here as arboreal species tend to be more slender and have longer tails and are therefore lighter relative to their lenght.
Snakes come in just about every colour. Some species such as the North American green snakes are uniform in their coloration whereas the pattern of others such as the Gaboon viper, are almost unbelievably intricate. Many diurnal snakes are striped whereas nocturnal or crepuscular species tend to be banded. Some vary from one individual to another, even when they are from the same clutch of eggs, and a few start off one colour and then change as they grow. These colour schemes, convenient though they are for identification, are not there for the benefit of herpetologists. Each has a role to play in helping the snake to survive. Furthermore, their role in survival may be primarily defensive, as in camouflage, or physiological, in increasing the absorption of heat or protecting vital organs from excessive radiation.

Frequency of shedding depends on many factors . As shedding is to some extent dependent on growth, young snakes tend to shed more often than adults because they grow more quickly . As their growth rate slows down , so does the frequency of shedding . All snakes shed occasionally , howver , even those that have all but stopped growing . In temperate species that go through a resting period , or hibernation , during the winter , shedding often takes place early in the spring almost as soon as they become active . Sexual activity is often heightened during the days immediately following this vernal shed .
Female snakes often shed their skins just before laying eggs or giving birth to live young . Snakes that have been injured often shed frequently , sometimes shedding several times in rapid succession even though they have not eaten between sheds . This is presumably under hormonal control and serves to speed up the rate of healing .
The shed skin of a snake is moist and supple immediately after shedding , due to the oily substance present , and the new skin of the snake may be similarly slightly tacky . After a few hours , however , this wears off and the shed skin becomes brittle . Shed skins are appreciably longer than the snakes from which they have come away , by up to 20 percent .


The Senses Of Snakes : Snakes have some of the same senses-sight , smell , etc . - that other animals use , but they have also evolved additional sesnses , perhaps because their eyesight and hearing are not very good . Snakes use their tongues to pick up scent particles from the athmosphere . First they flick their tongue about in the air and then withdraw it into their mouth . There they insert the tip of each fork into a pair of small chambers in the roof of their mouths : these chambers form the JACOBSON's organ , which is connected directly to the brain . Although snakes can also smell through their nostrils , the tongue and the jacobson s organ enhance this sense . Three groups of snakes - the boas , pythons and vipers - have an additional sense organ not seen in other animals .

These are heat pits , and are found on the face . Each pit is large and is lined with a sensitive membrane that detects the heat . In this way , species with pits can pinpoint the position of warm-blooded animals , which form their main prey , even in total darkness . Furthermore , by comparing the signals recieved by the pits on either side of their heads , they can even judge the distance to their prey and therefore strike accurately .
Boas and Pythons have a series of pits , located in the scales bordering the upper and lower lips ; boas have the pits between the scales and pythons have them within scales . In pit vipers , however , there is a single pit on each side of the head , located just below an imaginary line drawn between the eye and the nostril .


Feeding : Snakes'diets greatly depend on their size . They all eat other animals but , as they have no limbs to help them handle and dismember their prey , they must swallow it whole . In order to get around this limitation , their jaws are modified in such a way that they can be dislocated temporarily when swallowing , and their skin is very elastic . By these means , a snake can tackle prey larger than its head . The food of the very largest snakes , then , may include small deer and even crocodiles . Most snakes , however , usually feed on smaller prey , such as mice , rats , frogs , lizards and fish . A surprisingly large number specialise in eating other snakes , which are , of course , the ideal shape to be swallowed .
The method of capturing prey takes several forms . Some species , especially those that eat frogs , fish , worm and other small animals , eat their prey live - they just pick it up and begin swallowing . The boas and pythons , as well as many other species , constrict their prey , throwing several coils of their body around it and tightening their grip until it cannot breathe : they do not crush their prey , but suffocate it . Snakes from four families have venom fangs . These species inject their prey with powerful venoms that kill it quickly and efficiently . In this way the snake avoids the possible risk of injury while it is overpowering its prey .

Defense : Snakes have many many enemies and they have several means of preventing themselves from being killed or eaten . The most effective and common method is to avoid detection . Many are well camouflaged so that they blend in to their natural surroundings : tree snakes are green and brown , desert snakes may be yellow or light brown , etc . Others have very intricate markings consisting of blotches , bands or stripes and these are intended to confuse predators by disguising the outline of the snake . Yet other species are brightly coloured , with contrasting bands of red , yellow , white , black and so on . This is to warn or frighten potential enemies , but it may also create an optical illusion : When the snake moves and the bands flicker quickly past , the predator may be confused as to which directrion the snake is travelling .
If a snake fails to avoid detection , or if its warning colours do not deter an enemy , it may resort to other means of defense . Many species bite , even though only a few are venomous , and a number of them hiss and puff up their bodies in order to appear larger and fierce than they are . Others form themselves into a ball , with their heads safely tucked away among the coils and they may raise their tail and wave it about as if it is their head . A few play dead by turning over onto their backs and allowing their tongue to hang out of their mouths ; this is often accompanied by the secretion of a foul-smelling substance from glands at the base of their tail .
The rattle snake have a unique way of warning their enemies : their rattle is formed from parts of old shed skins , which are trapped by a constriction at the end of their tail . Each time the snake sheds its skin a new segment added and the rattle gets longer (although the end of the rattle may get broken off from time to time) . By vibrating its tail , the rattle snake makes a loud buzzy noise , warning predators that it is dangerous and also alerting large animals , such as a cattle , to its presence .


Reproduction : Reproduction is quite varied among snake species . Most lay eggs , which have a pliable shell through which water is absorbed during the development of the embryo . These egss are laid in a secluded place with a stable temperature and some moisure . Snake eggs can take up to three months to hatch and the female that lays them usually plays no part in their future development . Female pythons , however , brood their eggs by coiling around them throughout the incubation period . They control their temperature by transferring heat from their bodies to the eggs and some species even produce a small amount of heat to keep warm their eggs . We did't understand this process yet and we don't know how are they producing heat .
Other species retain their eggs inside their bodies , without shells , until they are at the point of hatching . Their young are fully formed when born . Giving the birth to live young is an adaptation to cold environments : by retaining the eggs inside their bodies the females can help the incubation along by basking and keeping their bodies warm . Snakes that lay eggs must rely on the weather to provide enough heat for incubation . Other groups of snakes are live-bearing for other reason : aquatic snakes , including most of the sea snakes , are unabe to lay eggs because they rarely , if ever , come onto the land . Similarly , tree-dwelling species tend to be live-bearing to avoid having to move down to ground level .
A single species of snake , the Brahminy Blind Snake is parthenogenic . This means that there are only females of this species . Once they reach breeding size they start to lay eggs without needing to mate with a male . Allof the eggs hatch into females .
Young snakes are able to fend for themselves as soon as they hatch or are born . They usually shed their skin within a few days and then they search for a suitable place to live and hunt for food . Growth rates vary , but small species may be large enough to breed within one year ; medium-sized snakes take two to four years to reach maturity , and large snakes , such as boas and pythons , take at least four years sometimes longer .


Habitats : Although temperature limits their activity and numbers in countries with cool climates , in tropical region snakes have moved into many habitats . They are totally aquatic snakes , including sea snakes , snakes that live their entire lives beneath the ground and others that spend much of their time in the upper branches of huge forest trees . Each species is well adapted to its habitat , in shape , colour and behaviour , leading to a much wider variety of size , shape and colour than is generally realised .


Snakes Becoming Increasingly Rare : Many snakes are becoming increasingly rare . Although many reasons contribute to their decline , habitat destruction is the most important one . Numerous habitats are shrinking , through the activies of agriculture , forestry , urbanisation and road building . Some species are protected and collecting or distrubing them is illegal . Unfortunately , these measures only protect individual snakes : thousands are killed by road traffic each year and hundreds of thousands die because the places where they live destroyed or altered . Snakes have an important role in the web of life . Many do a useful job of controlling the number of rodents and other pests and they all have a right to exist .

Balik Lagi