Crotalus cerastes

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Crotalus cerastes

Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Genus: Crotalus
Species: C. cerastes
Binomial name
Crotalus cerastes
Hallowell, 1854
Synonyms
  • Crotalus cerastes - Hallowell, 1854
  • C[audisona]. cerastes - Cope, 1867
  • Caudisona (Aechmophrys) cerastes - Coues In Wheeler, 1875
  • Aechmophrys cerastes - Coues In Wheeler, 1875
  • Crotalus cerastes - Boulenger, 1896
  • Crotalus cerastes [cerastes] - Klauber, 1944[1]
Common names: sidewinder, horned rattlesnake, sidewinder rattlesnake,[2] more.

Crotalus cerastes is a venomous pitviper species found in the desert regions of the southwestern United States and northwestern Mexico. Three subspecies are currently recognized, including the nominate subspecies described here.[3]

Contents

[edit] Description

A small species, with adult specimens measuring between 43 cm and 76 cm in length.[2] According to Campbell and Lamar (2004), most adults are 50-80 cm in length.[4] The females are larger than the males, which is unusual for this group of snakes.[5]

Midbody there are usually 21 rows of keeled dorsal scales.[2][6] In males there are 141 ventral scales or less; in females 144 or less.[2] Sometimes referred to as the horned rattlesnake because of the raised supraocular scales above its eyes. This adaptation may help shade the eyes or prevent sand drifting over them as the snake lies almost buried in the sand.[5]

The color pattern consists of a ground color that may be cream, buff, yellowish brown, pink or ash gray, overlaid with 28-47 dorsal blotches that are subrhombic or subelliptical.[4] In the nominate subspecies, the belly is white and the proximal lobe of the rattle is brown in adults. Klauber and Neill describe the ability of this species to display different coloration depending on the temperature -- a process known as metachrosis.[2]

[edit] Common names

Sidewinder, horned rattlesnake, sidewinder rattlesnake, Mojave Desert sidewinder (for C. c. cerastes),[2] sidewinder rattler.[7]

[edit] Geographic range

In the southwestern United States this species is found in the desert region of eastern California, southern Nevada, extreme southwestern Utah and western Arizona. In northwestern Mexico it is found in western Sonora and eastern Baja California. The type locality is listed as the "borders of the Mohave river, and in the desert of the Mohave" (California).[1]

[edit] Conservation status

This species is classified as Least Concern (LC) on the IUCN Red List of Threatened Species (v3.1, 2001).[8] Species are listed as such due to their wide distribution, presumed large population, or because it is unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend is stable. Year assessed: 2007.[9]

[edit] Behavior

Sidewinder tracks in Death Valley National Park.
Sidewinder tracks in Death Valley National Park.

The common name sidewinder is an allusion to its unusual form of locomotion, which is thought to give it traction on windblown desert sand, but this peculiar locomotor specialization is used on any substrate that the sidewinder can move over rapidly. As its body progresses over loose sand, it forms a letter-J shaped impression, with the tip of the hook pointing in the direction of travel. Sidewinding is also the primary mode of locomotion in other desert sand dwellers, such as the horned adder (Bitis caudalis) and Peringuey's adder (Bitis peringueyi), but many other snakes can assume this form of locomotion when on slick substrates (e.g., mud flats).

The species is nocturnal during hot months and diurnal during the cooler months of its activity period, which is roughly from March to November (probably longer in the southern part of its range).

[edit] Reproduction

Females produce up to 18 young, with an average of about 10 per litter. Like most other viperids, the young are born enveloped in thin embryonic membranes out of which they emerge shortly after being expelled from the mother. The young stay with their mother in a burrow for 7–10 days, shed for the first time, then leave their natal burrow. During this time, it is thought that the mother guards and protects them from predators.

Juvenile Sidewinders use their tails to attract lizard prey (see video: [1]), a behavior termed "caudal luring." Adult Sidewinders lose this behavior as they make the transition from lizard prey to their primary diet of desert rodents.

Sidewinders give birth to live young. The two most important events in a sidewinders calendar are mating and birth. Some females take a year off of breeding and only breed every other year. Some even rest for two years, if the food supply is scarce. Sidewinders mate in April through May and sometimes in fall. When the male and female mate, the male snake crawls along the female's back, rubbing her with his chin to stimulate or arouse her. The male then will wrap his tail around her tail and then will try to bring their clocque together. The clocque is a little flap that is near tail which is designed for mating and reproduction. If the female wants to mate, she will lift her tail and allow him to mate with her. The snakes can be mating for several hours, and if one of the snakes decides to move, the other is dragged along. Females might mate with the same male snake or a different male snake. In case their is a different male snake, the female has a good selection of genes for her young and increases the chances that at least some of her young will fit to survive. Females give birth to 15-18 young in late summer to early fall. The young are born 6 to 8 inches long. The birth takes only 2 to 3 hours altogether. Within a few minutes after being born, the baby sidewinder escapes out of a thin transparent membrane. The young stay near their birth place for a few days and then they disappear and have no future contact with their mother or their littermates. The sidewinder does not migrate over long distances, so being in the some area with one of their littermates isn't unlikely.

The sidewinder's life span varies. Sidewinders can live up to 20 to 30 years in captivity. In the wild, many of their lives are cut short because of predation, diseases, or vehicle accidents.

[edit] Venom

These snakes are venomous, but possess a weaker venom than many other rattlesnakes. This, together with the smaller size of their venom glands, makes them less dangerous than their larger cousins. Still, any bite should be taken seriously and medical attention sought immediately.

Norris (2004) lists the following venom yields: 33 mg average and 63 mg maximum (Klauber, 1956), and 30 mg average and 80 mg maximum (Glenn & Straight, 1982).[10] Brown (1973) gives a venom yield of 33 mg (Klauber, 1956) and LD50 values for mice of 2.6 mg/kg IV, 3.0, 4.0, 2.3 mg/kg IP and 5.5 mg/kg SC for toxicity. With these figures, Brown calculated that the LD50 for an adult human being weighing 70 kg would be 385 mg (SC).[11]

Bites can cause pain, swelling, hemorrhagic bleb formation and ecchymosis. Any swelling is usually not particularly severe, but it can involve all of the affected limb as well as the trunk. Systemic symptoms can include nausea, dizziness, chills, coagulopathy and shock.[10] Klauber (1997) includes an account of a man who had been bitten on the first joint of the index finger of the right hand, with only a single fang penetrating. Although the bite itself was described as no more painful than a pin prick, a doctor was seen within about 25 minutes and 10 cc of antivenin had been administered, within 2.5 hours his entire arm had swelled and the pain was violent, "as if the arm were soaked in a bucket of boiling oil."[12]

[edit] Subspecies

Subspecies[3] Authority[3] Common name[12] Geographic range[2]
C. c. cerastes Hallowell, 1854 Mojave Desert sidewinder In the United States in the desert areas from northeastern Los Angeles County and San Bernardino County, California, northward to southern Mono County, California, east across Nevada to Washington County, Utah, and south through Mohave County, Arizona. Desert lowlands at elevations between 152 and 1,829 m.
C. c. cercobombus Savage & Cliff, 1953 Sonoran Desert sidewinder In the United States from Yuma, Maricopa, Pima and Pinal counties in Arizona, southward into Sonora, Mexico.
C. c. laterorepens Klauber, 1944 Colorado Desert sidewinder The desert areas in the United States from central and eastern Riverside County, California, to Pinal County, Arizona, south to northwestern Sonora in Mexico, and northwest to northeastern Baja California. From the Colorado River to the desert foothills at elevations between 152 and 610 m.

[edit] See also

[edit] References

  1. ^ a b 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 d e f g Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN 0-8014-0463-0.
  3. ^ a b c Crotalus cerastes (TSN 174311). Integrated Taxonomic Information System. Retrieved on 5 February 2007.
  4. ^ a b Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
  5. ^ a b Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4.
  6. ^ Behler JL, King FW. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. LCCCN 79-2217. ISBN 0-394-50824-6.
  7. ^ Carr A. 1963. The Reptiles. Life Nature Library. Time-Life Books, New York. LCCCN 63-12781.
  8. ^ Crotalus cerastes at the IUCN Red List. Accessed 13 September 2007.
  9. ^ 2001 Categories & Criteria (version 3.1) at the IUCN Red List. Accessed 13 September 2007.
  10. ^ a b Norris R. 2004. Venom Poisoning in North American Reptiles. In Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.
  11. ^ Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. ISBN 0-398-02808-7.
  12. ^ a b Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. University of California Press, Berkeley. ISBN 0-520-21056-5.

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