Crotalus helleri

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Southern Pacific rattlesnake
Crotalus viridis helleri.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Crotalus
Species:
C. helleri
Binomial name
Crotalus helleri
Meek, 1905
Synonyms [1]
  • Crotalus helleri
    Meek, 1905
  • Crotalus viridis helleri
    — Klauber, 1949 [2]
  • Crotalus oreganus helleri
    — Ashton et al., 2001

Crotalus helleri or Crotalus oreganus helleri, also known commonly as the Southern Pacific rattlesnake, [3] the black diamond rattlesnake, [4] and by several other common names, is a pit viper species [5] or subspecies [3] found in southwestern California and south into Baja California, Mexico, that is known for its regional variety of dangerous venom types. It is sometimes considered a subspecies of Crotalus oreganus . [3]

Contents

Etymology

The specific or subspecific name, helleri, is in honor of American zoologist Edmund Heller. [6] [7]

Description

C. helleri Crotalus viridis .jpg
C. helleri

Adults of C. helleri are 24–55 inches (61–139 cm) in total length (including tail). [4]

The color pattern consists of a pale brown, gray-brown, or yellowish brown ground color overlaid with a series of large, dark brown dorsal blotches that may or may not have pale centers. [8] The blotches are more diamond shaped, as opposed to those of C. o. oreganus that are more hexagonal, [4] and are bordered by light scales. The tail rings are not clearly defined. [9] In juveniles, the end of the tail is bright orange, but this turns to brown as the snakes mature. In adults, the base of the tail and the first segment of the rattle are brown. The postocular stripe is moderately to very clearly defined. In juveniles, this stripe is bordered above by a pale stripe, but as the snakes mature this turns to drab yellow or brown. A conspicuous pale crossbar is sometimes present across the supraoculars, after which the head is a uniform dark color. In some older snakes the head is mostly dark with almost no trace of the supraorbital crossbar, or none at all. [8]

Common names

Common names for C. helleri include Southern Pacific rattlesnake, [3] [4] black diamond rattlesnake, black (diamond) rattler, gray diamond-back, mountain rattler, Pacific rattler, and San Diegan rattler. [4]

Venom varieties

Some populations of C. helleri have a neurotoxic venom that is very similar to the extremely dangerous Mojave rattlesnake (the "Mojave Green") toxin in the way it attacks the nervous system. [10] Other populations can have hemotoxic and myotoxic venom that is more typical among rattlesnakes and though less dangerous, can also can give a fatal bite. [11] [12] Thus, depending on where the bite was sustained, envenomation from this snake can require a much higher dose of Crotalidae polyvalent immune fab ("Crofab"), an antivenom used to treat the bite of North American pit vipers, [13] than the venoms of other rattlesnakes, including the venom of C. helleri specimens of different provenance. [12] In a survey of various populations of Crotalus in California, every sampled specimen with disabling neurotoxic venom had originated near Idyllwild, California, in the San Jacinto Mountains. [10] Scientists considered the intraspecific variety of venom types "medically significant", while hypothesizing that evolutionary pressures, driven by regional habitat differences and the associated challenges of hunting prey in each, could have been behind the variation of venom types in C. helleri, and that cross-breeding with the Mojave rattlesnake, which is geographically separated from neurotoxic Crotalus populations, was unlikely. [10] [14]

Behavioral variations

Scientists studying the dwarf species of C. Helleri inhabiting California's Santa Catalina Island found that these snakes "attempted to bite 4.7-fold more often than mainland snakes" of the same species, and that "the island snakes delivered 2.1-fold more venom when biting" than their mainland counterparts. [15]

Geographic range

C. helleri, juvenile Crotalus viridis Southern Pacific Rattlesnake Juvenile.jpg
C. helleri, juvenile

C. helleri is found in the United States in southern California, and in Mexico in northern Baja California, west of the desert. In the north it is found from the counties of San Luis Obispo and Kern, and south through the counties of Santa Barbara, Ventura, Los Angeles (including Santa Catalina Island and the foothills), southwestern San Bernardino, Orange, western Riverside, San Diego and extreme western Imperial. From there its range extends south through Baja California to lat. 28° 30' North. [16] According to Klauber (1956), the type locality is "San Jose, Lower California" [San José, lat. 31° N, Baja California (state), Mexico]. [2]

Related Research Articles

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<span class="mw-page-title-main">Rattlesnake</span> Group of venomous snakes of the genera Crotalus and Sistrurus

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<i>Crotalus</i> Genus of snakes

Crotalus is a genus of pit vipers, commonly known as rattlesnakes or rattlers, in the family Viperidae. The genus is found only in the Americas from southern Canada to northern Argentina. The generic name Crotalus is derived from the Greek word κρόταλονkrótalοn, which means "rattle" or "castanet", and refers to the rattle on the end of the tail, which makes this group so distinctive. As of July 2023, 44 to 53 species are recognized as valid.

<i>Crotalus scutulatus</i> Species of snake

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<span class="mw-page-title-main">Timber rattlesnake</span> Species of reptile

The timber rattlesnake, canebrake rattlesnake, or banded rattlesnake is a species of pit viper endemic to eastern North America. Like all other pit vipers, it is venomous, with a very toxic bite. C. horridus is the only rattlesnake species in most of the populous Northeastern United States and is second only to its relatives to the west, the prairie rattlesnake, as the most northerly distributed venomous snake in North America. No subspecies are currently recognized.

<span class="mw-page-title-main">Eastern diamondback rattlesnake</span> Species of reptile endemic to the southeastern US

The eastern diamondback rattlesnake is a species of pit viper in the family Viperidae. The species is endemic to the Southeastern United States. It is one of the heaviest venomous snakes in the Americas and the largest rattlesnake. No subspecies are recognized.

<span class="mw-page-title-main">Black-tailed rattlesnake</span> Species of snake

The black-tailed rattlesnake is a venomous pit viper species found in the southwestern United States and Mexico. Four subspecies are currently recognized, including the nominate subspecies described here.

<i>Crotalus basiliscus</i> Species of reptile

Crotalus basiliscus, known as the Mexican west coast rattlesnake, Mexican green rattler, and also by other names, is a species of pit viper in the family Viperidae. The species is endemic to western Mexico. Like all other pit vipers, it is venomous. The specific name, basiliscus, is derived from the Greek word for king, βασιλισκος, and alludes to this snake's large size and potent venom. No subspecies are currently recognized.

<i>Crotalus ruber</i> Species of snake

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<span class="mw-page-title-main">Western diamondback rattlesnake</span> Species of snake

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<i>Crotalus viridis</i> Species of snake

Crotalus viridis is a venomous pit viper species native to the western United States, southwestern Canada, and northern Mexico. Currently, two subspecies are recognized, including the prairie rattlesnake, the nominate subspecies, and the Hopi rattlesnake.

<i>Crotalus catalinensis</i> Species of venomous pit viper native to Isla Santa Catalina, Mexico

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<i>Crotalus viridis nuntius</i> Subspecies of snake

Crotalus viridis nuntius is a venomous pit viper subspecies native primarily to the desert plateau of the northeastern portion of the American state of Arizona, but also ranges into northwestern New Mexico. Named for the Native American Hopi tribe, which inhabits the region, its range overlaps that of the nominate subspecies and some interbreeding is believed to occur. The taxonomy of the C. viridis group is a matter of debate, many considering the various subspecies to be nothing more than locality variations.

<i>Crotalus durissus</i> Species of snake

Crotalus durissus, known as the South American rattlesnake, tropical rattlesnake, and by other names, is a highly venomous pit viper species found in South America. It is the most widely distributed member of its genus. Currently, seven subspecies are recognized.

<i>Crotalus oreganus</i> North American rattlesnake

Crotalus oreganus, commonly known as the Western rattlesnake or northern Pacific rattlesnake, is a venomous pit viper species found in western North America from the Baja California Peninsula to the southern interior of British Columbia.

<i>Crotalus atrox tortugensis</i> Subspecies of snake

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<span class="mw-page-title-main">Tiger rattlesnake</span> Species of snake

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<i>Crotalus concolor</i> Species of snake

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References

  1. ↑ "Crotalus oreganus ". The Reptile Database. www.reptile-database.org.
  2. 1 2 McDiarmid RW, Campbell JA, Touré TA (1999). Snake Species of the World: A Taxonomic and Geographic Reference, Volume 1. Washington, District of Columbia: Herpetologists' League. 511 pp. ISBN   1-893777-00-6 (series). ISBN   1-893777-01-4 (volume).
  3. 1 2 3 4 "Crotalus oreganus helleri ". Integrated Taxonomic Information System . Retrieved 28 November 2006.
  4. 1 2 3 4 5 Wright AH, Wright AA (1957). Handbook of Snakes of the United States and Canada. Ithaca and London: Comstock Publishing Associates, a division of Cornell University Press. (7th printing, 1985). 1,105 pp. (in two volumes). ISBN   0-8014-0463-0. (Crotalus viridis helleri, pp. 1014–1018, Figure 290 + Map 67 on p. 951).
  5. ↑ Crotalus helleri at the Reptarium.cz Reptile Database . Accessed May 7, 2023.
  6. ↑ Beltz, Ellin (2006). Scientific and Common Names of the Reptiles and Amphibians of North America – Explained. ebeltz.net/herps/biogappx/html.
  7. ↑ Beolens, Bo; Watkins, Michael; Grayson, Michael (2011). The Eponym Dictionary of Reptiles. Baltimore: Johns Hopkins University Press. xiii + 296 pp. ISBN   978-1-4214-0135-5. (Crotalus viridis helleri, p. 120).
  8. 1 2 Campbell JA, Lamar WW (2004). The Venomous Reptiles of the Western Hemisphere. 2 volumes. Ithaca and London: Comstock Publishing Associates. 870 pp., 1500 plates. ISBN   0-8014-4141-2.
  9. ↑ 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. (Crotalus viridis helleri, pp. 694–695 + Plate 627).
  10. 1 2 3 Sunagar, Kartik; Undheim, Eivind A.B.; Scheib, Holger; Gren, Eric C.K.; Cochran, Chip; Person, Carl E.; Koludarov, Ivan; Kelln, Wayne; Hayes, William K.; King, Glenn F.; Antunes, Agosthino; Fry, Bryan Grieg (2014). "Intraspecific venom variation in the medically significant Southern Pacific Rattlesnake (Crotalus oreganus helleri): Biodiscovery, clinical and evolutionary implications". Journal of Proteomics. 99: 68–83. doi:10.1016/j.jprot.2014.01.013. PMID   24463169. Archived from the original on 2021-05-07. Retrieved 2022-06-26.
  11. ↑ "Rattlesnakes". Archived from the original on 2012-04-08. Retrieved 2012-05-18.
  12. 1 2 "Rattlesnakes Two Hours Apart Pack Totally Different Venoms". National Geographic Society . 27 January 2014. Archived from the original on 27 June 2022. Retrieved 26 June 2022.
  13. ↑ "CroFab". savagelabs.com. Archived from the original on 2016-03-03.
  14. ↑ French, Wendy J.; Hayes, William K.; Bush, Sean P.; Cardwell, Michael D.; Bader, Julia O.; Rael, Eppie D. (2004). "Mojave toxin in venom of Crotalus helleri (Southern Pacific Rattlesnake): Molecular and geographic characterization". Toxicon. 44 (7): 781–791. Bibcode:2004Txcn...44..781F. doi:10.1016/j.toxicon.2004.08.008. PMID   15500854. Archived from the original on 2022-06-27. Retrieved 2022-06-27.
  15. ↑ Hayes, William K.; Person, Carl E. (18 March 2024). "Paradoxical Exception to Island Tameness: Increased Defensiveness in an Insular Population of Rattlesnakes". Toxins. 16 (3): 157–177. doi: 10.3390/toxins16030157 . PMID   38535823.
  16. ↑ Klauber LM (1997). Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. First published in 1956, 1972. Berkeley, California: University of California Press. 1,476 pp. (in two volumes). ISBN   0-520-21056-5.

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