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By Anders Nielsen, Ph.d.
Rattlesnakes belong to a genus named Crotalus consisting of numerous sub-species. The name rattlesnake has its origin in the rattle at the tip of their tails. The rattle is primarily used as a warning device when threatened.
Envenomations from rattlesnakes account for a significant portion of all poisonings in North America (Schaper et al., 2004)1, and apparently, the number of Rattlesnake bites is increasing.
Even in Europe, the number of rattlesnake bites is increasing because more and more people keep rattlesnakes as pets (ibid).
From the perspective of the rattlesnake, the purpose of a bite is to stun or kill a prey instantaneously. If the prey escapes the envenomation, the rattlesnake will follow its trail, wait until it is completely weakened, and eventually swallow it.
Rattlesnakes are capable of adjusting the amount of venom they use. If the rattlesnake only feels threatened, it may not deliver a full dose of poison into the attacker. However, a frightened or injured rattlesnake, or an inexperienced rattlesnake, may not be able to exercise such control.
Bites on humans usually occur when the snake is provoked or disturbed. Usually people are unaware of the range and speed of rattlesnakes, which even when coiled, is astonishing. They are also capable of striking uncoiled.
If you hike in rattlesnake territory, consider wearing pants and footwear reinforced with leather. If you encounter a Rattlesnake on a trail, keep your distance, and allow it to escape.
Rattlesnakes give live birth, and the female looks after the newborns for 7-12 days after birth.
Most rattlesnake species have hemotoxic venom, which acts by destroying tissue and preventing blood clotting. In itself, the venom has a lower toxicity than venom from many other venomous snakes, but because of the volume of venom the rattlesnake can deliver, it is extremely dangerous.
Amputation of limbs and permanent scars are two visible consequences of rattlesnake bites. Approximately 1/200 receiving a bite from a rattlesnake will die because of the bite, even when antivenom is used in the treatment. A normal diamondback rattlesnake bite contains sufficient venom to cause fatalities in a total of 50 people, indicating that the majority of envenomations are relatively low dosis.
Some tropical species have neurotoxic venom. Victims of these tropical rattlesnakes will usually succumb due to suffocation in combination with malfunctioning of either lungs and or the circulatory system.
A rattlesnakes rattle is composed of modified scales from the tail. A new segment is added to the rattle every time it sheds it skins. If the rattle did not break, one could determine the age of the snake by looking at the numbers of rattle segments. A rough age estimate is, however, obtained by merely counting the segments on the rattle. The rattlesnake sheds its skin when it has grown large enough, and this will also depend on prey availability, weather conditions, etc. Under wet conditions, the rattle cannot make any noise, and newborn rattlesnakes cannot rattle either.
In general,rattlesnakes are not aggressive. However, occasionally the Mojave rattlesnake may behave aggressively towards humans. The Mojave rattlesnake is larger than most other rattlesnakes, ranging from 20 to 50 inches (0.5-1.3 m) in size.
Its coloration varies from olive green to yellow green, while its back is lined with dark grey diamond shaped markings resembling the ones observed on thediamondback rattlesnake. The tail of the Mojave is light grey to white with very short black bands. Its preferred habitat is in the desert and in areas with many shrubs. The Mojave forages during the night and prefers small animals, such as mice and rats.
The diamondback rattlesnake is a large rattlesnake (30-84 inches) known by its diamond gray blotches on its back and its side. Its base color is a brown or gray, and its tail has alternating white and black rings. It also prefers areas with rocks and shrubs. It feeds on every animal that can be swallowed, even rabbits. They stand their ground when provoked and are considered very dangerous. It gives live birth (eggs hatch inside the female body) to small diamondback rattlesnakes with a length of approximately 8-12 inches. They can be found in many western parts of the U.S.
The sidewinder rattlesnake is one of the smallest rattlesnakes, ranging in size from 25 to 40 inches (0.6-1 m). Its preferred niche is sandy or loamy soil and sand. It likes hiding in the shade of bushes during daytime. A dark stripe is seen from its eyes, and the coloring of the body is brownish or grayish. It primarily feeds on small rodents and lizards.
1Schaper A, de Haro L, Desel H, Ebbecke M, Langer C "Rattlesnake bites in Europe - Experiences from southeastern France and northern Germany", Journal of Toxicology-clinical Toxicology 42(5) pp. 635-641 (2004)
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