Crotalus lepidus

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Crotalus lepidus
Crotalus lepidus lepidus 1.jpg
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Family: Viperidae
Genus: Crotalus
Species:C. lepidus
Binomial name
Crotalus lepidus
(Kennicott, 1861)
Crotalus lepidus distribution.png
Synonyms
  • Caudisona lepida Kennicott, 1861
  • A[ploaspis]. lepida Cope, 1867
  • Crotalus lepidus Cope, 1883
  • Crotalus [tigris var.] palmeri Garman, 1887
  • Crotalus palmeri Günther, 1895
  • Crotalus lepidus
    Boulenger, 1896
  • Crotalus lepidus lepidus
    Gloyd, 1936 [2]
Common names: rock rattlesnake, green rattlesnake, blue rattlesnake, more

Crotalus lepidus is a venomous pit viper species found in the southwestern United States and northern central Mexico. Four subspecies are currently recognized, including the nominate subspecies described here. [3]

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.

In biology, a species ( ) is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. While these definitions may seem adequate, when looked at more closely they represent problematic species concepts. For example, the boundaries between closely related species become unclear with hybridisation, in a species complex of hundreds of similar microspecies, and in a ring species. Also, among organisms that reproduce only asexually, the concept of a reproductive species breaks down, and each clone is potentially a microspecies.

United States federal republic in North America

The United States of America (USA), commonly known as the United States or America, is a country composed of 50 states, a federal district, five major self-governing territories, and various possessions. At 3.8 million square miles, the United States is the world's third or fourth largest country by total area and is slightly smaller than the entire continent of Europe's 3.9 million square miles. With a population of over 327 million people, the U.S. is the third most populous country. The capital is Washington, D.C., and the largest city by population is New York City. Forty-eight states and the capital's federal district are contiguous in North America between Canada and Mexico. The State of Alaska is in the northwest corner of North America, bordered by Canada to the east and across the Bering Strait from Russia to the west. The State of Hawaii is an archipelago in the mid-Pacific Ocean. The U.S. territories are scattered about the Pacific Ocean and the Caribbean Sea, stretching across nine official time zones. The extremely diverse geography, climate, and wildlife of the United States make it one of the world's 17 megadiverse countries.

Contents

Description

C. lepidus Mottled Rock Rattlesnake.JPG
C. lepidus

This small species rarely exceeds 32 in (81.3 cm) in length. It has a large, rounded head, and fairly heavy body for its size, with eyes with vertical pupils. Like other rattlesnakes, its tail has a rattle, which is composed of keratin. Each time the snake sheds its skin, a new segment is added to the rattle. However, the rattle is fragile and may break off, and the frequency of shedding can vary. So, the snake's age cannot be determined by the number of segments or length of the rattle.

Eye organ that detects light and converts it into electro-chemical impulses in neurons

Eyes are organs of the visual system. They provide organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons. In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods.

Pupil part of an eye

The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina. It appears black because light rays entering the pupil are either absorbed by the tissues inside the eye directly, or absorbed after diffuse reflections within the eye that mostly miss exiting the narrow pupil.

Keratin one of a family of fibrous structural proteins; protein that protects epithelial cells from damage or stress

Keratin is one of a family of fibrous structural proteins. It is the key structural material making up hair, nails, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin.

The color pattern varies greatly, but generally reflects the color of the rock in the snake's natural environment. Snakes found near areas of predominantly limestone tend to be a light grey in color, with darker grey banding. Snakes found at higher altitudes have darker colors. Specimens of the mottled rock rattlesnake (C. l. lepidus) from the Davis Mountains region often exhibit a more pink coloration, with dark-grey speckling rather than distinct banding. The banded rock rattlesnake (C. l. klauberi) gets its common name from its distinctive, clean banding, often with little speckling or mottling.

Common names

Its common names include: blue rattlesnake, eastern rock rattlesnake, green rattlesnake, little green rattlesnake, pink rattlesnake, rock rattlesnake, Texas rock rattlesnake, and white rattlesnake. [4]

Geographic range

This snake is found in the Southwestern United States (Arizona, southern New Mexico, and southwestern Texas) and northern central Mexico. The type locality given is "Presidio del Norte and Eagle Pass" (Texas, USA). H.M. Smith and Taylor (1950) emended the type locality to "Presidio (del Norte), Presidio County, Texas". [2]

Southwestern United States Geographical region of the USA

The Southwestern United States, also known as the American Southwest, is the informal name for a region of the western United States. Definitions of the region's boundaries vary a great deal and have never been standardized, though many boundaries have been proposed. For example, one definition includes the stretch from the Mojave Desert in California to Carlsbad, New Mexico, and from the Mexico–United States border to the southern areas of Colorado, Utah, and Nevada. The largest metropolitan areas are centered around Phoenix, Las Vegas, Tucson, Albuquerque, and El Paso. Those five metropolitan areas have an estimated total population of more than 9.6 million as of 2017, with nearly 60 percent of them living in the two Arizona cities—Phoenix and Tucson.

Arizona state of the United States of America

Arizona is a state in the southwestern region of the United States. It is also part of the Western and the Mountain states. It is the sixth largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona shares the Four Corners region with Utah, Colorado, and New Mexico; its other neighboring states are Nevada and California to the west and the Mexican states of Sonora and Baja California to the south and southwest.

New Mexico State of the United States of America

New Mexico is a state in the Southwestern region of the United States of America; its capital and cultural center is Santa Fe, which was founded in 1610 as capital of Nuevo México, while its largest city is Albuquerque with its accompanying metropolitan area. It is one of the Mountain States and shares the Four Corners region with Utah, Colorado, and Arizona; its other neighboring states are Oklahoma to the northeast, Texas to the east-southeast, and the Mexican states of Chihuahua to the south and Sonora to the southwest. With a population around two million, New Mexico is the 36th state by population. With a total area of 121,590 sq mi (314,900 km2), it is the fifth-largest and sixth-least densely populated of the 50 states. Due to their geographic locations, northern and eastern New Mexico exhibit a colder, alpine climate, while western and southern New Mexico exhibit a warmer, arid climate.

Conservation status

This species is classified as Least Concern IUCN Red List of Threatened Species (v3.1, 2001). [1] Species are listed as such due to their wide distribution, presumed large population, or because they are unlikely to be declining fast enough to qualify for listing in a more threatened category. The population trend was stable when assessed in 2006. [5]

IUCN Red List inventory of the global conservation status of biological species

The IUCN Red List of Threatened Species, founded in 1965, has evolved to become the world's most comprehensive inventory of the global conservation status of biological species. It uses a set of criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world, With its strong scientific base, the IUCN Red List is recognized as the most authoritative guide to the status of biological diversity. A series of Regional Red List are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.

However, it is listed as a threatened species by New Mexico, although Texas does not protect it. Its habitat is largely inaccessible, and not currently threatened by human development, though it is gradually becoming more and more fragmented.

Behavior

In general, these snakes are not aggressive. They tend to rely heavily on their camouflage, and will often not strike or even rattle their tails unless physically harassed. They spend most of their lives in rocky outcroppings and talus slopes, from which they are named. Man-made road cuts are often a favorite place. They are primarily nocturnal. Most people who get bitten by the rock rattlesnake are often hiking among rocks, where it lives. If someone steps or accidentally touches it, the snake's immediate reaction is to bite.

Feeding

Their diets consist of small mammals, lizards, and sometimes frogs. They are often more active at colder temperatures than other rattlesnake species.

C. l. lepidus Crotalus lepidus lepidus 2.jpg
C. l. lepidus

Captivity

Two subspecies, C. l. lepidus and C. l. klauberi , are frequently available in the exotic animal trade, and are well represented in zoos around the world. They are sought after for their wide array of potential colorations and typically docile nature. Most available are wild-caught; captive breeding, while not unheard of, is not commonplace. The two subspecies found only in Mexico are not often found in captivity outside of Mexico.

Reproduction

These snakes are ovoviviparous. They breed once a year, in the spring, and give birth about four months later to six to eight young. The young generally look like miniature versions of the parents and take three or more years to mature.

Venom

Their venom is primarily a haemotoxin, but has been known to have significant neurotoxic effects, as well. While not type-specific, the polyvalent antivenin CroFab is generally used to treat serious envenomations.

Subspecies

SubspeciesTaxon authorCommon nameGeographic range
C. l. klauberi Gloyd, 1936Banded rock rattlesnake Arizona, New Mexico, Texas, Mexico (south to Jalisco)
C. l. lepidus Kennicott, 1861Mottled rock rattlesnake New Mexico, Texas, Mexico (Chihuahua)
C. l. maculosus W. Tanner, Dixon & Harris, 1972Durango Rock rattlesnake Mexico (Durango, Sinaloa, Nayarit, Jalisco)
C. l. morulus Klauber, 1952Tamaulipan rock rattlesnake Mexico (Sierra Madre Oriental)

A recent review [6] showed that the Tamualipan rock rattlesnake appears to be a separate species, Crotalus morulus

See also

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References

  1. 1 2 Hammerson, G.A.; Frost, D.R. & Santos-Barrera, G. (2007). "Crotalus lepidus". IUCN Red List of Threatened Species. Version 2007. International Union for Conservation of Nature . Retrieved 5 June 2017.
  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. "Crotalus lepidus". Integrated Taxonomic Information System . Retrieved 15 May 2007.
  4. Wright AH, Wright AA. 1957. Handbook of Snakes. Comstock Publishing Associates. (7th printing, 1985). 1105 pp. ISBN   0-8014-0463-0.
  5. 2001 Categories & Criteria (version 3.1) at the IUCN Red List . Accessed 13 September 2007.
  6. Bryson Jr., R. W., C. W. Linkem, M. E. Dorcas, A. Lathrop, J. M. Jones, J. Alvarado-Díaz, C. I. Grünwald, and R. W. Murphy. 2014. Multilocus species delimitation in the Crotalus triseriatus species group (Serpentes: Viperidae: Crotalinae), with the description of two new species. Zootaxa 3826: 475–496

Further reading