Introduction.
Snakes are well known, albeit if a little misunderstood, animals; they are surrounded by many myths and misconceptions. My purpose with this article is to clear up some of these myths surrounding them and to better inform you about them.
What makes a snake a snake?
Snakes are cold-blooded vertebrates; they are limbless or nearly limbless reptiles. That said, some of the oldest species of snakes (like boas & pythons) have the remains of hind limbs & a pelvis. The remnants of the hind limbs are called cloacal spurs, which are located on both sides of the body right after the base of the tail. The origins of snake is still unknown, but there are 2 main hypothesis. One of which is that snakes evolved from ancient burrowing lizards. The other theory is that they evolved from ancient aquatic reptiles from the cretaceous era. Their know relatives include turtles, crocodiles, and lizards, among living reptiles.
Anatomy.
A snake’s skin is covered with elongated scales made of keratin (the same stuff that makes up our fingernails) aligned in single files from their heads to their tails. They shed their skins periodically and grow new ones. This moulting process allows them to grow and to get rid of parasites in their old skins.
Most snakes have teeth, four rows on the top and two on the bottom; however, only poisonous snakes have fangs. Fangs are long, sharp teeth connected to glands in the head which generate a poisonous liquid known as venom, which is a form of highly modified saliva. Technically the term poisonous snake is incorrect because poison is ingested while venom is injected, so the correct term is venomous snake. Ironically, venom milked from snakes also produces the cure to their venom.
Snakes have no eyelids, their eyes are covered with one large transparent scale called a spectacle. This supports the theory that snake evolved from water reptiles because the spectacle would be perfectly suited for underwater conditions. It would prevent the loss of water through osmosis while still allowing visibility.
They have middle and inner ears but no outer ear openings. They “hear” through vibrations in the ground.
Few snakes have two lungs, in the majority the left lung has been either lost or has been so reduced that it is now useless.
The bones in a snake’s skull are not connected in the same way as the bones in the skull of other reptiles. The bones are more loosely connected to each other and to the brain case; their lower jaws are separate in front. This special adaptation means that virtually the whole head is capable of being stretched and contorted.
Senses.
In most snakes vision is quite well developed; though, by human standards they are very shortsighted. Biologists know little about a snake’s eyes, but it appears that for the most part snakes can only detect movement.
As aforementioned, snakes have neither external ears nor eardrums. However they are still capable of hearing by detecting vibration in the ground. They do this by picking up vibrations with the bones in their lower jaws then transmitting them to their inner ears. The vibrations are transmitted via a delicate bony rod in close contact with it.
Snakes are capable of detecting odor using their tongues; although, some snakes are also able to smell using their noses. They move their tongue in and out through a gap in the upper lip, bringing odor particles into the roof of their mouths. The odor particles pass through a pair of duct openings to a special olfactory chamber. This chamber is known as the Jacobson’s organ. Though in fact, the tongue itself cannot detect odors it only helps bring the odor particles into the Jacobson’s organ. Their sense of smell is a key element in their lives; they use it for finding prey, finding mates, detecting predators, and to stimulate during courtship. Some snakes are unique among reptiles, all vertebrates really, they have a special type of organ that is capable of detecting the heat of warm-blooded prey. These organs are known as pit organs.
Mating.
Snakes usually find mates by their sense of smell, following reproductive odors released for tracking and for courtship. Once a male has found a mate he begins to court her, in most cases courtship involves contact. When the female is ready to mate she lifts her tail, so that the male twist his tail to meet the female’s cloaca with his own. Copulation can last anywhere from an hour to more than a day.
Most species reproduce once a year. The female will copulate several times during a breeding season, with the same or with different males, if the opportunity presents itself.
Snakes reproduce by either giving birth to fully formed young (viviparous) or by laying eggs (oviparous).
Only a few species brood their eggs after they have laid them. Examples of these species include the Carpet python, the Indian python and the Water python.
Conclusion.
Snake are amazingly interesting creatures that we know not nearly enough of. Reptiles in general are underrated but snakes are the worst off. We should make an effort to learn more about them to make them a little less alien to us. Who Knows, maybe you will be the person to finally prove were snake come from.
Bibliography
Zug, George R., and Carl H. Ernst.Snakes. 2. ed. Washington, D.C.: Smithsonian Books, 2004. Print.
“Snake.” Wikipedia, the Free Encyclopedia. Web. 05 Nov. 2011. .