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Rattlesnakes are a group of venomous New World snakes, genera Crotalus and Sistrurus. They belong to the class of venomous snakes known commonly as pit vipers. There are nearly thirty species of rattlesnake, with numerous subspecies. They are named for the rattle found at the tip of their tails that is used as a warning device when threatened. Most rattlesnakes mate in the spring, and all species give live birth. Mothers care for their young after birth for seven to ten days.


 


This image is the work of an U.S. Fish and Wildlife Service employee, taken or made during the course of an employee's official duties. As a work of the U.S. federal government, the image is in the public domain. For more information, see the Fish and Wildlife Service copyright policy.Shake, RATTLE, and roll: 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 several times a year depending on food supply and growth rates and since the rattle can and does break, there is little truth to the claim that one can tell a rattlesnake's age from the number of beads in its rattle. Newborn rattlesnakes do not have functional rattles; it isn't until after they have shed their skin for the first time that they gain an additional bead, which beats against the first bead, known as the button, to create the rattling sound. Adult snakes may lose their rattles on occasion, but more appear at each molting. In wet weather if the rattle has absorbed sufficient water, it will not make noise.

Some discretion, please: Even with a useful rattle, a rattlesnake might not always give warning. Some speculate that rattlesnakes that use their rattles around humans are often killed and natural selection may favor rattlesnakes that do not give advance warning.

Startled Snake!: Different species of rattlesnake vary significantly in size, territory, markings, and temperament. If the rattlesnake is not cornered or imminently threatened, it will usually attempt to flee from encounters with humans, but will not always do so. Bites often occur when humans startle the snake or provoke it. Those bitten while provoking rattlesnakes have usually underestimated the range and speed with which a coiled snake can strike. Heavy boots and long pants reinforced with leather or canvas are recommended when hiking in areas known to harbor rattlesnakes.

Life Lessons: For learning how to quickly and safely identify rattlesnakes by their markings, guides are available through booksellers, libraries, and local conservation and wildlife management agencies. The best way to avoid contact with rattlesnakes is to remain observant and avoid potential encounters. Hikers should always watch their steps when negotiating fallen logs or boulders and take extra caution when near rocky outcroppings and ledges where rattlesnakes may be hiding or sunning themselves. Pets should be kept leashed to prevent them from provoking a rattlesnake.


A Venomous Mouth: Rattlesnakes are born with fully functioning fangs capable of injecting venom and can regulate the amount of venom they inject when biting. Generally they deliver a full dose of venom to their prey, but may deliver less venom or none at all when biting defensively. A frightened or injured snake may not exercise such control. Additionally, young snakes may have not yet learned to control the amount of venom they deliver. Some studies contest that young snakes may be capable of injecting less venom, and the high toxicity of their bite comes from a variation in their venom which causes it to have a more potent concentration than in their adult counterparts. Any bite from a rattlesnake should be considered fully venomous and those bitten should seek medical attention immediately.

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 Kingdom: Animalia

 Phylum: Chordata

 Class: Reptilia

 Order: Squamata

 Family: Viperidae

 Subfamily: Crotalinae