Crotalus concolor

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Crotalus concolor
Crotalus oreganus concolor 01.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. concolor
Binomial name
Crotalus concolor
Woodbury, 1929
Faded Rattlesnake 2.svg
Geographical range of the Midget Faded Rattlesnake [1]
Synonyms
  • Crotalus concolor
    Woodbury, 1929
  • Crotalus confluentus decolor Klauber, 1930
  • Crotalus confluentus concolor– Woodbury, 1930
  • Crotalus viridis concolor
    – Klauber, 1936
  • Crotalus viridis decolor
    – Gloyd, 1940
  • Crotalus viridis decolor
    – Klauber, 1956
  • Crotalus viridis concolor
    – Klauber, 1972 [2]
  • Crotalus oreganus concolor
    – Ashton & de Queiroz, 2001 [3]

Crotalus concolor, commonly known as the midget faded rattlesnake, [4] faded rattlesnake, [5] and yellow rattlesnake, [6] is a pit viper species found in the western United States. [4] [7] It is a small rattlesnake known for its faded color pattern. Like all other pit vipers, it is venomous.

Contents

Description

The color pattern of this species consists of a pinkish, pale brown, yellow-brown, straw-colored, reddish, or yellow-brown ground color, overlaid with a series of brown elliptical or rectangular dorsal blotches. However, most specimens are gray or silvery. In juveniles, the pattern is distinct, but becomes faded in adults, almost to the point where it is indistinguishable from the ground color. [8] This has led to the snake sometimes being locally referred to as the "horseshoe rattler." [9]

Adult individuals typically measure between 50 and 60 cm (20 to 24 inches) in length, although they can reach up to 75 cm (30 inches). [9] This is notably shorter than the typical western rattlesnake, which can grow up to 126 cm (64 inches). [9] The smallest gravid female measured was 52.2 cm (20+1⁄2 in). [10]

Males are generally larger than females, and the snakes weigh around 120 g (4.2 oz), although they can weigh as much as 200 g (7.1 oz). [9] Newborns of this subspecies are 50 to 100 mm (2 to 4 inches) shorter than other western rattlesnake subspecies and weigh about half as much. [11] [12] [13]

The scales are keeled, and the snake has an entire anal plate. Like all rattlesnakes, the tail ends in a horny rattle, with the number of tail rings indicating the number of molts the snake has undergone. [9]

The venom of the Midget Faded Rattlesnake is neurotoxic and is considered one of the most potent among Crotalid venoms. [14] The snakes are generally non-aggressive when left undisturbed. [14]

Geographic range

Found in the United States in the Colorado and Green River basins. This area covers southwestern Wyoming, Utah east of long. 111° West (excluding the southeastern corner) and extreme west-central Colorado. [10] The type locality given is "King's Ranch, Garfield Co., at the base of the Henry Mts [Utah]." [2]

Diet and Feeding Behavior

The Faded Rattlesnake is a prey generalist that employs a sit-and-wait ambush strategy for hunting. A study done in 2007 identified 25 different prey items consumed by this species, most of which were identified through palpation or voluntary regurgitation by the snakes. [15] The identified prey items included 16 lizards, six small mammals, and three birds, such as Deer Mouse ( Peromyscus maniculatus ), Wood Rat ( Neotoma albigula ), and various Sceloporus species. [15]

Spatial trends in prey consumption have been observed, with lizards primarily consumed in rocky areas and mammals and birds consumed in sagebrush steppes where lizards are less common. [16] However, the study did not report prey preference based on the snake's age class or any other characteristics.

Ontogenetic shifts in prey preference have been noted, with a transition from primarily consuming lizards to mammals as the snakes grow. [17] This shift is similar to what has been observed in other rattlesnake species, although no corresponding shift in venom composition was noted. [17]

In Arizona specifically, the diet of Crotalus concolor is largely unknown. However, one observation noted the snake consuming Ord's Kangaroo Rat ( Dipodomys ordii ), adding a new species to the known prey items for this rattlesnake. [18]

During predatory and defensive contexts, Crotalus concolor has been found to inject similar amounts of venom into both mice and lizards, despite the mass of envenomated mice being four times greater than that of the lizards. [19]

Habitat and Movement Behavior

This species predominantly inhabits high, cold deserts characterized by sagebrush ( Artemisia (plant) ) and an abundance of rock outcrops and exposed canyon walls. [20] Greasewood ( Sarcobatus vermiculatus ), juniper ( Juniperus scopulorum ), and other woody plants are also present, sometimes even dominating certain areas. Juniper woodlands are more prevalent at higher altitudes. [20]

Rock outcrops serve as focal points for these rattlesnake populations, providing escape cover, thermal cover, and hibernacula. [20] These outcrops are particularly important given the short warm seasons and long, cold winters in the snake's range. The snakes often den in groups, sometimes comprising up to 100 individuals. [20] In Wyoming, where the subspecies reaches its northern limits, the distribution of suitable denning outcrops is a key factor in the snake's distribution. [20]

After emerging from hibernation in April and May, the snakes stay near the den entrance for 2 to 3 weeks before moving to "shedding habitats," characterized by large flat rocks that assist in molting. [20] Adult males and non-gravid females typically migrate an average of 2,122 m and 1,956 m, respectively, while gravid and post-partum females usually move only about 297 m. [20]

Aggregating behavior is common among Midget Faded Rattlesnakes. They often aggregate during gestation, and young snakes stay with their mother for about a week after birth. [20] This behavior is thought to be an adaptation to environmental pressures, enhancing predator defense as well as osmo- and thermoregulation. [20]

Gravid females typically move less than 20 m from their hibernaculum upon emergence. Males and non-gravid females, on the other hand, have some of the longest migrations and largest activity ranges reported for rattlesnakes. [20] The snakes have separate winter/spring and summer activity ranges and make shorter, more random movements primarily associated with hunting during the summer. [20]

Venom

This species possesses the most toxic venom of the C. oreganus / C. viridis group, although apparently considerable variability exists among local populations. [14] It is even one of the most potent venoms found in North America, [14] and according to LD50 studies, the venom is many times more potent than that of an Asiatic cobra. [21] It is characterized by the presence of a presynaptic neurotoxin, referred to as concolor toxin, the amount of which varies in individual snakes. [14] [22] [8] In rattlesnakes, venom is generally categorized into two types: Type I, which has high metalloprotease activity and lower toxicity, and Type II, characterized by high toxicity neurotoxins. [23] Unlike some other rattlesnakes that undergo an ontogenetic shift in venom composition, C. concolor does not show significant changes in venom toxicity as it matures. This phenomenon is termed "venom paedomorphosis," where the snake retains its juvenile venom characteristics into adulthood. [24] [17]

The venom of C. concolor is particularly potent, being 5–30 times more lethal than that of other Western Rattlesnake species. [14] It contains a potent presynaptic phospholipase A2-based neurotoxin, known as "concolor toxin," which blocks the release of acetylcholine from nerve axon terminals, resulting in rapid prey immobilization. [17] [25] The venom also contains non-enzymatic peptide myotoxins, which further contribute to its toxicity. [23] [26]

Human envenomations by C. concolor are rare, likely due to the snake's remote habitat and generally mild disposition. [27] Symptoms of envenomation can include numbness, swelling, loss of balance, vomiting, and more. [28] Treatment with CroFab antivenom is recommended and has been found to be effective even when administered 52 hours post-envenomation. [28]

Related Research Articles

<span class="mw-page-title-main">Venom</span> Toxin secreted by an animal

Venom or zootoxin is a type of toxin produced by an animal that is actively delivered through a wound by means of a bite, sting, or similar action. The toxin is delivered through a specially evolved venom apparatus, such as fangs or a stinger, in a process called envenomation. Venom is often distinguished from poison, which is a toxin that is passively delivered by being ingested, inhaled, or absorbed through the skin, and toxungen, which is actively transferred to the external surface of another animal via a physical delivery mechanism.

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

Crotalus cerastes, known as the sidewinder, horned rattlesnake or sidewinder rattlesnake, is a pit viper species belonging to the genus Crotalus, and is found in the desert regions of the Southwestern United States and northwestern Mexico. Like all other pit vipers, it is venomous. Three subspecies are currently recognized.

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

Rattlesnakes are venomous snakes that form the genera Crotalus and Sistrurus of the subfamily Crotalinae. All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting small animals such as birds and rodents.

<span class="mw-page-title-main">Snakebite</span> Injury caused by bite from snakes

A snakebite is an injury caused by the bite of a snake, especially a venomous snake. A common sign of a bite from a venomous snake is the presence of two puncture wounds from the animal's fangs. Sometimes venom injection from the bite may occur. This may result in redness, swelling, and severe pain at the area, which may take up to an hour to appear. Vomiting, blurred vision, tingling of the limbs, and sweating may result. Most bites are on the hands, arms, or legs. Fear following a bite is common with symptoms of a racing heart and feeling faint. The venom may cause bleeding, kidney failure, a severe allergic reaction, tissue death around the bite, or breathing problems. Bites may result in the loss of a limb or other chronic problems or even death.

<span class="mw-page-title-main">Snake venom</span> Highly modified saliva containing zootoxins

Snake venom is a highly toxic saliva containing zootoxins that facilitates in the immobilization and digestion of prey. This also provides defense against threats. Snake venom is injected by unique fangs during a bite, whereas some species are also able to spit venom.

<span class="mw-page-title-main">Inland taipan</span> Highly venomous snake native to Australia

The inland taipan, also commonly known as the western taipan, small-scaled snake, or fierce snake, is a species of extremely venomous snake in the family Elapidae. The species is endemic to semiarid regions of central east Australia. Aboriginal Australians living in those regions named the snake dandarabilla. It was formally described by Frederick McCoy in 1879 and then by William John Macleay in 1882, but for the next 90 years, it was a mystery to the scientific community; no further specimens were found, and virtually nothing was added to the knowledge of this species until its rediscovery in 1972.

<span class="mw-page-title-main">Envenomation</span> Process of venom injection

Envenomation is the process by which venom is injected by the bite or sting of a venomous animal.

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

Crotalus scutulatus, also known commonly as the Mojave rattlesnake, the Mojave green rattlesnake, and the Mohave rattlesnake, is a species of highly venomous pit viper in the family Viperidae. The species is native to the deserts of the southwestern United States and adjacent central Mexico. It is perhaps best known for its potent neurotoxic-hemotoxic venom, which is considered the world's most potent rattlesnake venom. Two subspecies are recognized as being valid, including the nominate subspecies described here.

<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">Venomous snake</span> Species of the suborder Serpentes that produce venom

Venomous snakes are species of the suborder Serpentes that are capable of producing venom, which they use for killing prey, for defense, and to assist with digestion of their prey. The venom is typically delivered by injection using hollow or grooved fangs, although some venomous snakes lack well-developed fangs. Common venomous snakes include the families Elapidae, Viperidae, Atractaspididae, and some of the Colubridae. The toxicity of venom is mainly indicated by murine LD50, while multiple factors are considered to judge the potential danger to humans. Other important factors for risk assessment include the likelihood that a snake will bite, the quantity of venom delivered with the bite, the efficiency of the delivery mechanism, and the location of a bite on the body of the victim. Snake venom may have both neurotoxic and hemotoxic properties. There are about 600 venomous snake species in the world.

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

Crotalus helleri or Crotalus oreganus helleri, known as the Southern Pacific rattlesnake, black diamond rattlesnake, and by other names, is a pit viper species or subspecies 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.

<span class="mw-page-title-main">Myotoxin</span>

Myotoxins are small, basic peptides found in snake venoms and lizard venoms. This involves a non-enzymatic mechanism that leads to severe muscle necrosis. These peptides act very quickly, causing instantaneous paralysis to prevent prey from escaping and eventually death due to diaphragmatic paralysis.

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

The western diamondback rattlesnake or Texas diamond-back is a rattlesnake species and member of the viper family, found in the southwestern United States and Mexico. Like all other rattlesnakes and all other vipers, it is venomous. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the greatest number of snakebites in the U.S. No subspecies are currently recognized.

<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 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.

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

The tiger rattlesnake is a highly venomous pit viper species found in the southwestern United States and northwestern Mexico. No subspecies are currently recognized. The specific name tigris,, refers to the many narrow dorsal crossbands, which create a pattern of vertical stripes when viewed from the side.

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

The Great Basin rattlesnake is a venomous pit viper species found in the Great Basin region of the United States.

<span class="mw-page-title-main">Evolution of snake venom</span> Origin and diversification of snake venom through geologic time

Venom in snakes and some lizards is a form of saliva that has been modified into venom over its evolutionary history. In snakes, venom has evolved to kill or subdue prey, as well as to perform other diet-related functions. While snakes occasionally use their venom in self defense, this is not believed to have had a strong effect on venom evolution. The evolution of venom is thought to be responsible for the enormous expansion of snakes across the globe.

Crotoxin (CTX) is the main toxic compound in the snake venom of the South American rattlesnake, Crotalus durissus terrificus. Crotoxin is a heterodimeric beta-neurotoxin, composed of an acidic, non-toxic and non-enzymatic subunit (CA), and a basic, weakly toxic, phospholipase A2 protein (CB). This neurotoxin causes paralysis by both pre- and postsynaptic blocking of acetylcholine signalling.

References

  1. ↑ Rattlesnakes of Arizona - Midget Faded Rattlesnake (Crotalus concolor). ECO Publishing. pp. 203–204.
  2. 1 2 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).
  3. ↑ Ashton KG, de Queiroz A. 2001. Molecular systematics of the western rattlesnake, Crotalus viridis (Viperidae), with comments on the utility of the d-loop in phylogenetic studies of snakes. Molecular Phylogenetics and Evolution, Vol. 21, No.2, pp. 176-189. PDF Archived 2007-09-29 at the Wayback Machine at CNAH. Accessed 3 September 2008.
  4. 1 2 Crotalus concolor at the Reptarium.cz Reptile Database. Accessed 11 December 2019.
  5. ↑ Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN   0-8014-0463-0.
  6. ↑ Woodbury, A. M. (1929). "A new rattlesnake from Utah". Bulletin of the University of Utah. 20 (6): 3.
  7. ↑ "Crotalus oreganus concolor". Integrated Taxonomic Information System . Retrieved 11 August 2007.
  8. 1 2 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.
  9. 1 2 3 4 5 G.T. Baxter, M.D. Stone (1985). Amphibians and reptiles of Wyoming. Second edition. Cheyenne, Wyoming, USA: Wyoming Game and Fish Department.
  10. 1 2 Klauber LM. 1997. Rattlesnakes: Their Habitats, Life Histories, and Influence on Mankind. Second Edition. 2 volumes. Reprint, University of California Press, Berkeley. ISBN   0-520-21056-5.
  11. ↑ L.M. Klauber (1972). Rattlesnakes: their habits, life histories, and influence on mankind. Second edition. Berkley, California, USA: University of California Press.
  12. ↑ J.M. Macartney, P.T. Gregory (1988). "Reproductive biology of female rattlesnakes (Crotalus viridis) in British Columbia". Copeia. 1988: 47–57.
  13. ↑ L.V. Diller, R.L. Wallace (1996). "Comparative ecology of two snake species (Crotalus viridis and Pituophis melanoleucus) in southwestern Idaho". Herpetologica. 52: 343–360.
  14. 1 2 3 4 5 6 J.L. Glenn, R. Straight (1977). "The midget faded rattlesnake (Crotalus viridis concolor) venom: lethal toxicity and individual variability". Toxicon. 15: 129–133.
  15. 1 2 J. M. Parker, S. H. Anderson (2007). "Ecology and behavior of the Midget Faded Rattlesnake (Crotalus oreganus concolor) in Wyoming". J. Herpetol. 41: 41–51.
  16. ↑ J. M. Parker (2003). The Ecology and Behavior of Midget Faded Rattlesnakes in Wyoming (Thesis). Laramie, Wyoming: University of Wyoming.
  17. 1 2 3 4 S. P. Mackessy, K. Williams, K. G. Ashton (2003). "Ontogenetic variation in venom composition and diet of Crotalus oreganus concolor: a case of venom paedomorphosis?". Copeia. 2003: 769–782.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  18. ↑ J. O. Whitaker, Jr. (1980). The Audubon Society Field Guide to North American Mammals. New York: Alfred A. Knopf.
  19. ↑ W. K. Hayes, S. S. Herbert, G. C. Rehling, J. F. Gennaro (2002). Biology of the Vipers. Eagle Mountain, Utah: Eagle Mountain Publishing, LC. pp. 207–234.{{cite book}}: CS1 maint: multiple names: authors list (link)
  20. 1 2 3 4 5 6 7 8 9 10 11 J.M. Parker (2003). The ecology and behavior of the midget faded rattlesnake in Wyoming (Thesis). Laramie, Wyoming, USA: University of Wyoming.
  21. ↑ "LD50 - intravenous". Archived from the original on 2011-07-16. Retrieved 2010-09-02.
  22. ↑ Wetstein et al., 1985
  23. 1 2 S. P. Mackessy (2010). "Evolutionary trends in venom composition in the Western Rattlesnakes (Crotalus viridis sensu lato): toxicity vs. tenderizers". Toxicon. 55: 1463–1474.
  24. ↑ S. P. Mackessy (1988). "Venom ontogeny in the Pacific Rattlesnakes Crotalus viridis helleri and Crotalus viridis oreganus". Copeia. 1988: 92–101.
  25. ↑ S. P. Mackessy (2009). Handbook of Venoms and Toxins of Reptiles. Boca Raton, Florida: Taylor and Francis Group. pp. 3–23.
  26. ↑ C. L. Ownby, S. D. Aird, I. I. Kaiser (1988). "Physiological and immunological properties of small myotoxins". Toxicon. 26: 319–323.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  27. ↑ G. L. Glenn, R. C. Straight (1990). "Venom characteristics as an indicator of hybridization between Crotalus viridis viridis and Crotalus scutulatus scutulatus in New Mexico". Toxicon. 28: 857–862.
  28. 1 2 V. Bebarta, R. Dart (2003). "Effectiveness of delayed use of Crotalidae polyvalent immune fab (ovine) antivenom". Journal of Toxinology: Clinical Toxicology. 41: 641–753.

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