Crotalus atrox

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iCrotalus atrox

Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Genus: Crotalus
Species: C. atrox
Binomial name
Crotalus atrox
Baird & Girard, 1853
Synonyms
  • Crotalus cinereous - Le Conte In Hallowell, 1852
  • Crotalus atrox - Baird & Girard, 1853
  • Crotalus adamanteus var. atrox - Jan, 1859
  • Caudisona atrox var. atrox - Kennicott, 1861
  • Caudisona atrox var. sonoraensis - Kennicott, 1861
  • C[rotalus]. adamanteus var. atrox - Jan, 1863
  • C[rotalus]. atrox var. sonoriensis - Jan, 1863
  • C[audisona]. atrox - Cope, 1867
  • Crotalus adamanteus atrox - Cope In Yarrow In Wheeler, 1875
  • Caudisona atrox var. sonorensis - Boulenger, 1896
  • Crotalus atrox atrox - Cope, 1900
  • [Cortalus] atrox sonoraensis - Amaral, 1929
  • Crotalus atrox - Klauber, 1972
  • Crotalus sonoriensis - Golay et al., 1993
  • Crotalus atrox - Golay et al., 1993[1]

Common names: western diamondback rattlesnake, western diamond-backed rattlesnake,[2] more.


Crotalus atrox is a venomous rattlesnake species found in the United States and Mexico. No subspecies are currently recognized.[2]

Contents

[edit] Description

C. atrox is generally colored a shade of dark or light brown. Its pattern is a distinctive row of large, dark diamond shapes edged in yellow trim, running down the length of its body. The diamonds fade to dark rings around the tail, where the distinctive rattle begins. A dark stripe edged in yellow runs back from the mouth to the eyes on each side of the head. There is no significant difference in appearance between males and females except that males are generally larger. They grow to an average length of 4½ feet, but can reach a maximum length 6½ feet.

Though large and bulky in appearance, C. atrox can strike up to two-thirds of its body length. That's about a three to four foot striking range for larger specimens. It strikes with two large, hollow fangs which inject venom into its prey eventually killing it (venom is lethal to small animals within minutes). The fangs are retractable and replaceable as venomous snakes lose and replace fangs often. Movement is in a rectili fashion (unlike sidewinders).

[edit] Diet

The diamondback eats small mammals and birds, and sometimes other reptiles, amphibians, fish, invertebrates, rabbits, mice, rats, gophers, sparrows, and ground squirrels. It eats every two to three weeks and swallows its food whole. The food is digested as it passes through the body. Its annual water consumption is about its body weight. In very dry areas it also absorbs water from its prey.

[edit] Common names

Western diamondback rattlesnake, western diamond-backed rattlesnake,[2] Adobe snake, Arizona diamond rattlesnake, coon tail, desert diamond-back, desert diamond rattlesnake, fierce rattlesnake, spitting rattlesnake, Texan rattlesnake, Texas diamond-back (rattlesnake).[3]

[edit] Behavior and reproduction

Western diamondbacks can live for more than twenty years, but life expectancy is typically shorter because of hunting and human expansion. Solitary outside of mating season, they are one of the more aggressive species found in North America because they rarely back away from confrontation. When threatened they usually coil and shake their rattle to warn an aggressor that it has stumbled upon something dangerous. There is suspicion that some rattlesnakes (and the diamondback in particular) which generally live around populated areas do not rattle as often because it leads to the snake’s discovery and consequent destruction. However, there is little available evidence of this hypothesis.

C. atrox, like other desert snakes, can go for up to two years without food in the wild. A 5½ month starvation study showed that the snakes reduced energy expenditures by an average of 80% over the length of the study. The snakes also feed from within on energy-rich lipid stores. The most interesting finding was that the snakes grew during the study, indicating that while the snake's mass was shrinking, it was putting its resources into skeletal muscles and bone.[4]

The snake is a poor climber and primarily hunts small mammals, but will also feed on birds, small reptiles and amphibians. They hunt (or ambush prey) at night or early morning using a type of infrared sense prominently found in pit vipers. Although adult specimens have no natural predators, hawks, eagles, and other snakes can prey on young or adolescent individuals.

Rattlesnakes, including C. atrox, are viviparous. Gestation period lasts six or seven months and broods average about a dozen young. However, the young only stay with the mother for a few hours before they set off on their own to hunt and find recluse, thus the mortality rate is very high.The Western Diamondback Rattlesnake is the most commonly encountered rattlesnake in Texas. The Western Diamondback is the longest rattlesnake in the state, and one of the two heaviest (the other is the Timber Rattlesnake). The record length is over 213 cm (84 in); adults found in the wild typically measure between 0.91-1.21 m (3-4 ft). Its common name does not come unearned; a series of diamond-shaped blotches runs down the length of its back, and each blotch is surrounded by a light border. A background coloration of tan or brown surrounds the blotches, and the dorsal coloration varies tremendously over its distributional range. This rattlesnake can easily be distinguished by its black and white tail, which also earns the western diamondback the name "coontail" (also, see below). Its off-white belly is usually unmarked, its anal scale is undivided, and its dorsal scales are extremely keeled, often in rows of 25 to 27 near midbody.

Similar species. -- Crotalus atrox may be confused with a number of snakes found in Texas, most of which are non-venomous. The majority of these snakes, however, lack the key feature of a rattle found at the end of the tail. Many snakes, including gopher snakes (Pituophis) and hognose snakes (Heterodon) may show an impressive threat display and have similar brown and tan markings, but lack the rattles. Some rattle-less snakes such as rat snakes and copperheads may vibrate their tails. Like all rattlesnakes, Crotalus atrox has a heat-sensing pit between the eye and nostril. The dorsal markings of rattlesnakes range from the distinct diamond-shaped (rhomboid) marks in Crotalus atrox and the Mojave Rattlesnake (Crotalus scutulatus), to dorsal blotches in the Prairie Rattlesnake (Crotalus viridis) and the Western Massasauga (Sistrurus catenatus), to narrower crossbands extending down the sides of the body in the Rock Rattlesnake (Crotalus lepidus). The pattern of the Western Diamondback is most similar to that of the Mojave Rattlesnake and the Prairie Rattlesnake. The color of the tail is a useful key to discriminate C. atrox from most other rattlesnakes. In C. atrox, the tail is completely encircled with white and black bands of equal widths. The Mojave Rattlesnake, Crotalus scutulatus, is the only other Texas rattlesnake with such prominent black and white bands around its tail, but the white bands are twice as wide as the black bands. Crotalus scutulatus does have similar dorsal rhomboid markings running the length of its body, yet these blotches flatten into bands in the posterior third of the body; the diamond markings of C. atrox do not flatten into bands. Adult Mojave Rattlesnakes usually reach lengths of only about three feet, so any very large rattlesnakes are most likely Western Diamondbacks.

Natural History. -- All rattlesnakes are venomous, and therefore potentially dangerous if approached or handled. Rattlesnakes are not generally aggressive and will most likely flee if given a chance to retreat. Found from the flatlands and prairies to the rocky hills and low mountains, the Western Diamondback is a key participant in the food web; it is an important predator of many small rodents, rabbits, and birds. The Western Diamondback is in turn preyed upon by a variety of larger mammals and birds, such as coyotes, foxes, and hawks. It is primarily a nocturnal animal, hunting for its prey on warm summer nights. It is, however, seasonally diurnal, moving between hunting sites during the day during the cooler spring and fall months. The Western Diamondback is usually inactive between late October and early March, though an occassional rattlesnake may be seen sunning itself on warm winter days. Mating occurs in the spring and the females give birth (they are viviparous) to as many as 25 young, which may be as long as 30 cm (12 in) in length. The young are fully capable of delivering a venomous bite hours after their birth.

Distribution. -- Crotalus atrox is found in California, Arizona, New Mexico, Oklahoma and Texas. The Western Diamondback also has an extensive range in the the northern half of Mexico. In Texas, Crotalus atrox is found throughout the state, save the wettest eastern portions of the state. Its relative, the Eastern Diamondback (Crotalus adamanteus), is found in eastern Louisiana and ranges from there through Florida to Northa Carolina.

[edit] Range & habitat

C. atrox is found both in the United States (South-East California, South Nevada, Arizona, New Mexico, Texas, Oklahoma, Arkansas) and in Mexico (Hidalgo). Habitat surroundings are similar to that of C. adamanteus but generally in more arid and rocky country. Nevertheless, they are also good swimmers.

[edit] Venom

Although the venom of the diamondback isn't particularly toxic, the size of the snake allows a larger capacity of venom which is released from its two prominent fangs. It's not uncommon that only one bite mark from one fang is visible after a strike. Fangs can break or bend, or the bite area may be small, causing a miss. All pit vipers have the ability to control the flow of venom through their fangs, allowing the diamondback to release most of its venom in a single strike (though often a pit viper will not release any of its venom). The venom capacity combined with the aggressiveness of the snake make it dangerous and lethal, and responsible for several recorded deaths.

Most of the toxin released is proteolytic like all other American pit vipers. Proteolytic venoms are, in fact, advanced and concentrated fluids that destroy tissues and other cells through intramolecular digestion. A few toxic effects include: cytotoxic (destoys cells), hemotoxic (destroys red blood cells), myotoxic (causes paralysis and muscle destruction), hemorrhagic (causes persistent bleeding). Smaller amounts of neurotoxins are also present. Rattlesnakes have the most potent hemotoxic venom of any snake, making them one of the most dangerous snakes in the world. Unlike neurotoxins, hemotoxin poisoning becomes quickly apparent; the area around the wound swells at a rapid rate. Discoloration and pain are also experienced shortly after being bitten. Professional medical attention should be sought immediately, especially when the victim is a child. The smaller the victim the less time it takes for the poison to spread. Although it is commonly believed that baby or young rattlesnakes deliver more concentrated venom and are thus more dangerous, this idea is not supported by scientific evidence. The amount of venom delivered is a much more important indicator of the bite's danger than the venom's concentration, and since larger (older) snakes can deliver much more venom, larger rattlesnakes should always be considered more dangerous.[1]

[edit] Captivity

C. atrox is frequently bred in captivity, and readily available in the exotic animal trade. Many color variations are bred, including albinos, patternless, and melanistic. They are also heavily collected from the wild, frequently being drawn out of their hiding places with gasoline, and used in rattlesnake roundups where they are killed for entertainment.[2] Despite this, their population is not considered to be threatened.

[edit] Gallery

[edit] See also

[edit] Cited references

  1. ^ McDiarmid RW, Campbell JA, Touré T. 1999. Snake Species of the World: A Taxonomic and Geographic Reference, vol. 1. Herpetologists' League. 511 pp. ISBN 1-893777-00-6 (series). ISBN 1-893777-01-4 (volume).
  2. ^ a b c Crotalus atrox (TSN 174310). Integrated Taxonomic Information System. Accessed on 28 November 2006.
  3. ^ Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-4014-0463-0.
  4. ^ Why Does A Starving Diamond-Back Continue To Grow? Optimism!. Retrieved on April 6, 2006..

[edit] Other references

[edit] External links

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