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Timber rattlesnake, C. horridus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Subfamily: Crotalinae
Genus: Crotalus
Linnaeus, 1758
  • Crotalus - Linnaeus, 1758
  • Crotalophorus - Houttuyn, 1764
  • Caudisona - Laurenti, 1768
  • Crotalinus - Rafinesque, 1815
  • Crotalurus - Rafinesque, 1820
  • Crotulurus - Rafinesque, 1820
  • Uropsophus - Wagler, 1830
  • Urocrotalon - Fitzinger, 1843
  • Aploaspis - Cope, 1867
  • Aechmophrys - Coues In Wheeler, 1875
  • Haploaspis - Cope, 1883
  • Paracrotalus - Reuss, 1930[1]
Common names: rattlesnakes, rattlers.[2]

Crotalus is a genus of venomous pitvipers found only in the Americas from southern Canada to northern Argentina.[1] The name is derived from the Greek word krotalon, which means "rattle" or "castanet", and refers to the rattle on the end of the tail that make this group so distinctive.[3] 29 species are currently recognized.[4]



Members of this genus range in size from only 50-60 cm (C. intermedius, C. pricei), to over 150 cm (C. adamanteus, C. atrox).[3] In general, adult males are slightly larger than females. Compared to most snakes they are heavy-bodied, although some African vipers are much thicker.[5] Most forms are easily recognized by the characteristic rattle on the end of the tail, although a few island populations form exceptions to this rule: C. catalinensis has lost its rattle entirely, C. ruber lorenzoensis usually has no rattle, and both C. r. lucasensis and C. molossus estebanensis exhibit a tendency for rattle loss. The rattle may also be lacking in any species due to a congenital abnormality.[3]

The rattle itself consists of a series of loosely interlocking hollow shells, each of which was at one point the scale covering the tip of the tail. In most other snakes, the tail tip, or terminal spine, is cone-shaped, hardly any thicker than the rest of the skin, and is shed along with it at each successive molt. In this case, however, the end-scale, or "button", is much thicker and shaped like a bulb with one or two annular constrictions that prevent it from falling off. Before each molt, a new button will have developed inside the last, one and before the skin is shed, the tip of new button shrinks, thereby loosening the shell of the previous one. This process continues so that a succession of molts produces an appendage that consists of a number of interlocking segments that make an audible noise when vibrated. Since younger specimens may shed 3-4 times in a year, every time adding a new segment to the rattle, the number of segments bears no relation to the age of the snake. In addition, end segments tend to break off after the rattle becomes about 6-7 segments long; it is uncommon to find specimens with as many as a dozen segments.[6][7]

Geographic range

Found in the Americas from southern Canada to northern Argentina.[1]


None are considered aggressive. In fact, when threatened most will retreat quickly. However, most species will defend themselves readily when cornered.[3]

A highly controversial issue has always been how far these snakes can strike. Obviously this depends on the size of the animal, but other factors may also play a role, such as the species, the position the body is in and the degree of excitement. Additionally, there is the question of definition: from which point on the snake should a strike be measured: from the front, the middle, or the back of the anchor coil on the ground? Even if the length of the specimen is known, once it strikes it is almost impossible to determine the limiting point reached by its head and the position of its body when the movement started. Therefore, it is not surprising that many conflicting statements can be found in the available literature about how far these snakes can strike. Estimates have been given that range from ⅓ of the body length, to ½, to ⅔, and even the full length of the animal. Klauber (1997) considered that they rarely strike further than ½ of their body length, and almost never more than ¾, but that it is still not wise to trust such values if only because it is not possible to accurately judge the length of a coiled snake.[5]


This genus is viviparous, giving birth to live young.[5]


Species[4] Authority[4] Subsp.*[4] Common name[3] Geographic range[1]
C. adamanteus Palisot de Beauvois, 1799 0 Eastern diamondback rattlesnake The southeastern United States from southeastern North Carolina, south along the coastal plain through peninsular Florida to the Florida Keys, and west along the Gulf Coast though southern Mississippi to southeastern Louisiana.
C. aquilus Klauber, 1952 0 Querétaro dusky rattlesnake The highlands of central Mexico: Guanajuato, Hidalgo, México, Michoacán and San Luis Potosí.
C. atrox Baird & Girard, 1853 0 Western diamondback rattlesnake The United States from central Arkansas and southeastern California, south into Mexico as far as northern Sinaloa, Hidalgo and northern Veracruz. Disjunct populations exist is southern Veracruz and southeastern Oaxaca.
C. basiliscus (Cope, 1864) 0 Mexican west coast rattlesnake Western Mexico from southern Sonora to Michoacán.
C. catalinensis Cliff, 1954 0 Santa Catalina rattlesnake Isla Santa Catalina in the Gulf of California (western Mexico).
C. cerastes Hallowell, 1854 2 Sidewinder The southwestern United States in the desert region of eastern California, southern Nevada, extreme southwestern Utah and western Arizona. In northwestern Mexico in western Sonora and eastern Baja California.
C. durissus Linnaeus, 1758 8 South American rattlesnake Found in all South American countries except Chile and Ecuador, although the various populations are disjunct. Also occurs on some islands in the Caribbean.[3]
C. enyo (Cope, 1861) 2 Baja California rattlesnake Western Mexico on the Baja California Peninsula from around Río San Telmo on the west coast and from opposite Isla Angel de la Guarda on the gulf coast, south to Cabo San Lucas. Also on the following islands in the Gulf of California: San Marcos, Carmen, San José, San Francisco, Partida del Sur, Espírita Santo and Cerralvo. Off the pacific coast it is also found on the island of San Margarita.
C. horridusT Linnaeus, 1758 0 Timber rattlesnake The eastern United Sates from southern Minnesota and southern Maine, south to east Texas and north Florida. Also in southern Canada in southern Ontario.
C. intermedius Troschel, 1865 2 Mexican small-headed rattlesnake Central and southern Mexico, in southeastern Hidalgo, southern Tlaxcala, northeastern and south-central Puebla, west-central Veracruz, Oaxaca and Guerrero.
C. lannomi Tanner, 1966 0 Autlán rattlesnake Western Mexico in Jalisco.
C. lepidus (Kennicott, 1861) 3 Rock rattlesnake The southwestern United States in Arizona, southern New Mexico and southwestern Texas, south into northern central Mexico.
C. mitchellii (Cope, 1861) 4 Speckled rattlesnake The southwestern United States in east-central and southern California, southwestern Nevada, extreme southwestern Utah and western Arizona. In Mexico in most of Baja California, including Baja California Sur. Also found on a number of islands in the Gulf of California and on Santa Margarita Island off the Pacific coast of Baja California Sur.
C. molossus Baird & Girard, 1853 3 Black-tailed rattlesnake The southwestern United States in Arizona, New Mexico and west and central Texas. In Mexico as far south as Oaxaca. Also found in the Gulf of California on San Estéban Island and Tiburón Island.
C. oreganus Holbrook, 1840 6 Western rattlesnake Southwestern Canada (southern British Columbia), south though much of the western half of the United States (Washington, Oregon, western and southern Idaho, California, Nevada, Utah, Arizona, and likely west-central New Mexico), and into northern Mexico (western Baja California (state) and the extreme north of Baja California Sur).[3]
C. polystictus (Cope, 1865) 0 Mexican lance-headed rattlesnake Central Mexican Plateau, from southern Zacatecas and northeastern Colima east to east-central Veracruz.
C. pricei Van Denburgh, 1895 1 Twin-spotted rattlesnake In the United States from southeastern Arizona and Mexico in northern Sonora southeast through Chihuahua, Durango, southeastern Cohuila and Nuevo León into Tamaulipas.
C. pusillus Klauber, 1952 0 Tancitaran dusky rattlesnake West-central Mexico in southwestern and west-central Michoacán and adjacent Jalisco. Probably also in northeastern Colima.
C. ruber Cope, 1892 2 Red diamond rattlesnake The United States in southwestern California, south through the Baja California Peninsula, except in the desert east of the Sierra de Juárez. Also found on a number of islands in the Gulf of California and two islands off the west coast of Baja California Sur.
C. scutulatus (Kennicott, 1861) 1 Mohave rattlesnake The southwestern United States in southern California, southern Nevada, extreme southwestern Utah, most of Arizona, southern New Mexico and western Texas, and south into Mexico to southern Puebla.
C. simus Latreille In Sonnini & Latreille, 1801 2 Middle American rattlesnake From Mexico in southwestern Michoacán on the Pacific coast, and Veracruz and the Yucatan Peninsula on the Atlantic coast, south through Belize, Guatemala, El Salvador, Honduras and Nicaragua to west-central Costa Rica.[3]
C. stejnegeri Dunn, 1919 0 Long-tailed rattlesnake Western Mexico in eastern Sinaloa, western Durango and probably northern Nayarit.
C. tigris Kennicott In Baird, 1859 0 Tiger rattlesnake The southwestern United States in south-central Arizona, and in northwestern Mexico in Sonora. Also found on Isla Tiburón in the Gulf of California.
C. tortugensis Van Denburgh & Slevin, 1921 0 Tortuga island diamond rattlesnake Mexico, on Tortuga Island, in the Gulf of California off the coast of Baja California Sur.
C. totonacus Gloyd & Kauffeld, 1940 0 Totonacan rattlesnake Northeastern Mexico from central Nuevo León through southern Tamaulipas, northern Veracruz, eastern San Luis Potosí and northern Querétaro.[3]
C. transversus Taylor, 1944 0 Cross-banded mountain rattlesnake Central Mexico in the states of México and Morelos.
C. triseriatus (Wagler, 1830) 1 Mexican dusky rattlesnake Mexico, along the southern edge of the Mexican Plateau in the highlands of the Transverse Volcanic Cordillera, including the states of Nayarit, Jalisco, Michoacán, Morelos, México, Puebla, Tlaxcala and Veracruz.
C. viridis (Rafinesque, 1818) 1 Prairie rattlesnake Southern Canada (Alberta, Saskatchewan), south through the United States (eastern Idaho, Montana, North Dakota, South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, Texas, New Mexico, extreme eastern Arizona), and into northern Mexico (northern Coahuila, northwestern Chihuahua).[3]
C. willardi Meek, 1905 4 Ridge-nosed rattlesnake The United States in southeastern Arizona and southwestern New Mexico, and northwestern Mexico in Sonora, Chihuahua, Durango and Zacatecas.

*) Not including the nominate subspecies (typical form).
T) Type species.[1]

See also


  1. ^ a b c d e 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. ^ 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 d e f g h i j 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.
  4. ^ a b c d Crotalus (TSN 174305). Integrated Taxonomic Information System. Accessed on 23 August 2007.
  5. ^ a b c 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.
  6. ^ Parker HW, Grandison AGC. 1977. Snakes -- a natural history. Second Edition. British Museum (Natural History) and Cornell University Press. 108 pp. 16 plates. LCCCN 76-54625. ISBN 0-8014-1095-9 (cloth), ISBN 0-8014-9164-9 (paper).
  7. ^ Stidworthy J. 1974. Snakes of the World. Grosset & Dunlap Inc. 160 pp. ISBN 0-448-11856-4.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Crotalus". A list of authors is available in Wikipedia.
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