We fear from them since they have the capability to kill us by their own venom. They are snakes. They are different from lizards since they lack eyelid and outside ears. They are ectothermic, amniotes covered by overlapping scales like the rest of the squamates. The skull bones of snakes are demarcated by existence of a high number of joints that let them feed on a prey which is much bigger than them. Jaws are highly movable. They have just one functional lung. Some species bear a set of vestigial claws on each side of the cloaca. They range in size from 10 cm such as that of thread snake to the larger pythons and anacondas that are about 7.6 meters long. The recently discovered fossil of snake Titanoboa was about 15 meters long.
Snakes are believed to have evolved out of their terrestrial or aquatic lizard ancestors during the Cretaceous period. Modern snakes appeared throughout the Paleocene period. Vast majority of the species are non-poisonous and the venomous species use their venom as a step of self-defence. Some venomous snakes have the potential to kill even humans. Non-venomous snakes either swallow the victim living or kill it by constriction. The modern English word snake comes from the Old English word snaca meaning to crawl or to creep. Fossil listing of snakes is relatively poor as the skeletons are comparatively modest making fossilization impossible. 150 million year old specimens of snakes are discovered in South America and South Africa. Fossil records suggest that the snakes have developed in the burrowing lizards. Primitive snakes among the contemporary ones are the pythons and the boas.
Skull consists of a good braincase to which other bones have been loosely articulated making the limbs elastic so that successful feeding and prey capture can begin. The left and right surfaces of the lower jaw are joined into a ligament while the posterior end of lower jaw is articulated with the quadrate making the jaw more portable. Mandibles and quadrate also help in choosing noise borne vibrations. Hyoid is a small bone located in the neck area serving for the attachment of the tongue muscles. Vertebral column comprises 200-400 vertebrae. Tail vertebrae fewer and lack ribs. Vertebrae of human anatomy endure two ribs. Vertebrae have strong articulation with muscles in order to bring about effective locomotion in absence of limbs. Autotomy is absent in snakes. Pythons and boas possess a pair of vestiges of hind limbs in the kind of pelvic spurs found on either side of the cloaca composed of the vestiges of ilium and femur.
The heart is enclosed in a membranous sac called pericardium present in the bifurcation of the bronchi. Heart can move from its location as diaphragm is absent. This house protects heart from harm when large prey eaten passes throughout the oesophagus. Spleen is located attached to gall bladder and pancreas and aids in blood flow. Thymus is situated just above heart and also is responsible for the generation of immune cells. Cardiovascular system of snakes is unique in using a renal portal system in which the blood out of snake’s tail passes through kidneys prior to returning back to heart. Damaged lung is vestigial and is even absent in some species. Nearly all species just 1 lung is functional. Anterior portion of lung is highly vascularized participating in gaseous market while the posterior section fails to do so. Saccular lung provides buoyancy to snake body. Lymph nodes are absent.
Belly scales are used for gripping on the surface. Eyelids are transparent and are often known as brille. Shedding of scales is called as ecdysis. In snakes the outer layer of the skin is shed as one layer. Scales are actually the derivatives of skin. Scales on head, back and belly are significant from taxonomic viewpoint. Scales are named on the basis of their status within the body. Moulting is quite important in snakes it serves two fold functions. It enables the snake from worn and old skin and second it helps to get rid of parasites and mites. Shedding of skin in the kind of moulting helps to grow in size and it occurs occasionally. Before moulting a snake stops feeding and hides itself in protective areas like underground burrows. Just before moulting skin gets tough, dry and eyes become muddy. Inner surface of skin liquefies helping the older skin to easily leave the body. Old skin breaks near the mouth and the snake pushes itself against the face and the old skin leaves the entire body in 1 layer. An elderly snake sheds its skin a couple of times a year. A younger growing snake may lose its skin four times annually so as to grow. Discarded skin provides an imprint of scale structure on the snake’s body assists in identification.
Snake vision varies considerably. They can only distinguish light and dark objects and the eyesight isn’t sharp but adequate so they can only trace motions. Vision is best in arboreal snakes but bad in the burrow dwellers. Asian blossom snake includes a binocular vision so both the eyes can focus on precisely the exact same point. Most snakes focus objects by back and forward motion of lens in connection with the retina while in others lens is elongated. Smell is utilized by snakes in prey tracking. Airborne vibrations are picked up from the bifid or forked tongue and are subsequently passed to the vomeronasal organ or the Jacobson’s organ for evaluation. Forked tongues assist in olfaction as well as tasting prey. Tongues are kept in continuous movement and allergens from air, ground and water are used for prey capture. The component of bodyin contact with ground is very sensitive to vibrations so they can sense any animal approaching near even with quite faint vibration.
Cobras, vipers and some related ones use venom so as to trap or kill prey. Certain birds, mammals and some snakes like the kingsnakes prey on venomous snakes and also have developed resistance in addition to immunity against the snake venom. Snake venom is a intricate mixture of proteins stored in poison glands at the back of your head. These glands open into hollow fangs which behave as hypodermic needles for injecting the venom into the victim’s entire body. The venom proteins can be a combination of neurotoxins, haemotoxins, cytotoxins and bungarotoxins along with other toxins. Venom has hyalouronidase enzyme which assists in rapid diffusion of venom in the victim’s body. Cobras and kraits have proteroglyphous fangs that stay permanently erect. Venomous snakes are classified in three taxonomic households like Elapidae comprising of cobras, kraits, mambas, coral snakes, sea snakes and Viperidae comprising vipers, rattlesnakes, copperheads, bushmasters. The next family is Colubridae surrounding boomslangs, tree snakes, vine snakes but all colubrids are not poisonous.
All snakes are strictly carnivorous feeding on fish, eggs, insects, small mammals and snakes. They swallow the prey as a whole. Poisonous snakes kill the prey with venom before consuming it other swallow the prey by constriction. After feeding they are dormant for effective digestion to take place. They are ectothermic so the outside temperature helps in digestion. Digestive enzymes help in the digestion of nails, claws, feathers and hairs. Even though the limbs are still absent but snakes have developed unique approaches to perform locomotion. Lateral undulation is the most usual manner of locomotion performed by both aquatic and aquatic snakes. In lateral undulation the body of snake flexes to right and left resulting in the creation of rearward moving waves. The snake moves quicker and high amount of energy must carry out this mode of locomotion.
Terrestrial lateral undulation is the most common manner of locomotion performed by property snakes. The posteriorly moving waves induce the body more closer to the contact points in the environment such as the trees, rocks etc. resulting in the creation of a forward thrust. Snake moves quicker even in thick or dense vegetation. While swimming the waves become more and the snake goes faster. Thrust is made by pushing the body against water. Sea snakes can perform reverse lateral undulation. Side winding is just another mode of locomotion adopted by colubrids such as vipers, elapids while going on a slick sand flat or sand dune. It’s a modified form of lateral undulation in which all of the body segments move in 1 direction and have been in contact with the floor while other segments are lifted up leading to rolling of body. This manner of locomotion aids in preserving the energy.
When the push-points are absent and the snake is not able to perform lateral undulation in addition to sidewinding like from the tunnels and the burrows then it moves by concertina locomotion. Inside this locomotion snake dentures that the upper portion of body against the tunnel wall while the front of head extends and straightens. Front portion is then relaxed and it stinks to shape a anchor and the posterior section now straightens and is pulled forwards. This is quite a manner of locomotion and requires high amount of energy. The slowest mode of locomotion is the rectilinear locomotion and it’s the sole mode of locomotion where the snake doesn’t bends its body. The belly scales are raised up and pulled forward before being put down and the body is pulled over them. Ribs don’t move in this mode of locomotion. It’s the most common mode of locomotion in pythons, boas and vipers.
The tree snakes perform locomotion differently which is very much determined by the bark of the tree in addition to on the species. Snakes utilize modified kind of concertina locomotion and might also creep by lateral undulation of touch points are available. Snakes move faster on small branches if contact points can be found. Fertilization in rodents is internal and is transported by means of hemipenes stored and stored from the tail of man snake. Most species are oviparous. Females of King cobra build nests for their eggs and protect them until they hatch. Many pythons coil around their eggs until they hatch. Some species are ovoviviparous and keep eggs within their bodies until they are ready to hatch.
Snakes in general prevent biting humans. The bite of the non-poisonous snakes is generally benign. Out of the 725 species of venomous snakes only 250 species endure the potential to kill humans in one bite. Australia averages just one deadly snake bite annually. In India about 250,000 deaths are recorded in a year by snake bite. Bite of a poisonous snake affects every part of human body. It causes nausea, fainting, increased appetite and head ache. Blood pressure becomes low and heartbeat increases. Muscle coordination diminishes. Respiration slows down. Nausea and vomiting are also common. Excessive bleeding occurs at the website of the sting. The snake venom could be treated with the help of anti-venom. Antivenom is species specific and is prepared by collecting the venom in the poison gland of the poisonous snakes and is then injected into the entire body of horse. The doses of venom are increased in the future till the horse is immunized. Blood is extracted from the immunized horse along with the serum is separated and processed and is allowed to freeze.
In this show the charmer plays music and the spider is seen to execute specific sorts of motions that are really a sort of defensive action in response to the motions of the flute. According to the Wildlife Protection Act of 1972 has banned such kinds of illegitimate acts. Snakes can also be consumed as food in certain parts of world. Snakes are also a famous delicacy in the kind of snake soups in certain Asian nations. In western world snakes are also reared as pets. Brazil is known as the Snake Island since it houses the largest population of snakes.
Though snakes appear hazardous but they help in keeping the environmental balance. Pest Experts are often called to remove them from private properties.