The Rattlesnake reference article from the English Wikipedia on 24-Jul-2004
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Rattlesnake

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Rattlesnakes
Scientific classification
Kingdom:Animalia
Phylum:Chordata
Class:Reptilia
Order:Squamata
Family:Viperidae
Genera:Crotalus
Sistrurus
Species
about 30
Rattlesnakes are a group of venomous New World snakes, genera Crotalus and Sistrurus, which have a small noise-making jointed rattle on their tails. If not surprised, they will usually use this rattle as a warning device when they feel threatened. The rattle is composed of a series of nested, hollow beads which are actually modified scales from the tail-tip. Each time the snake sheds its skin, a new rattle segment is added. Since they may shed their skins many times a year, and since the rattle can and does break, there is no truth to the claim that one can tell a rattlesnake's age from the number of rattles. There are about 30 species, with numerous subspecies.

Rattlesnakes are pit vipers. Pit vipers have heat-sensitive pits between the eye and the nostril that enable them to find prey very effectively. Pit vipers also have fangs in the upper part of the mouth that fold in when not in use. When a pit viper attacks, it unfolds the fangs, bites, and injects its venom.

Rattlesnake bites are generally not fatal for adult humans, if promptly and properly treated. Most (but not all) rattlesnake venom is primarily hemotoxic, meaning it destroys blood cells and other tissue and is often very painful. Permanent damage, including loss of an affected limb, is possible, even with prompt, effective treatment - a rattlesnake bite is always a potential serious injury.

Some rattlesnakes, especially the tropical species, have primarily neurotoxic venom. A bite from these snakes may not be very painful, but the venom can interfere with the function of the heart, and can paralyze the lungs. Prompt treatment is essential for any victim of a rattlesnake bite.

Different species of rattlesnake vary significantly with respect to temperament. Some are relatively docile, while some are quite aggressive when challenged. Rattlesnakes control the amount of venom they inject, generally delivering a full dose to prey, but less or none when biting defensively. A very significant exception to this is a provoked, enraged snake, which might not only deliver a full dose, but which may try to do so repeatedly. No matter the circumstance, always assume that venom has been injected and seek immediate help if bitten.

Rattlesnakes are born live and are born with fully functional fangs that deliver venom. Newborn rattlesnakes do not have functional rattles - only after several skin sheddings will a rattlesnake have a useful rattle. In wet weather, if the rattle has absorbed sufficient water, it will not make noise - another reason not to expect a warning from a rattlesnake. Even with a useful rattle, a rattlesnake might not always give a warning. There has been speculation that rattlesnakes that use their rattles around humans are often killed. Natural selection might favor rattlesnakes that don't give advance warning.

Table of contents
1 Species and Subspecies
2 References
3 External link

Species and Subspecies

(adapted from Rattlesnake Index)

References

External link