South American rattlesnake | |
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South American rattlesnake (Crotalus durissus terrificus) | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Reptilia |
Order: | Squamata |
Suborder: | Serpentes |
Family: | Viperidae |
Genus: | Crotalus |
Species: | C. durissus |
Binomial name | |
Crotalus durissus | |
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Synonyms | |
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Crotalus durissus, known as the South American rattlesnake, [2] tropical rattlesnake, [4] 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. [2] Currently, seven subspecies are recognized. [5]
The Guiana rattlesnake, previously recognized as C. d. dryinus, [3] is now considered a synonym for C. d. durissus. In fact, after the previous nominate subspecies for the C. d. durissus complex became the current nominate for Crotalus simus , which now represents its Mexican and Central American members, C. d. dryinus became the new nominate for the South American rattlesnakes as represented by C. durissus. [2] The subspecies previously known as C. d. collilineatus and C. d. cascavella were moved to the synonymy of C. d. terrificus following the publication of a paper by Wüster et al. in 2005.
Subspecies [ref 1] | Taxon author [ref 1] | Common name | Geographic range |
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C. d. cumanensis | Humboldt, 1833 | Venezuelan rattlesnake [ref 2] | Dry lowlands of Venezuela and Colombia |
C. d. durissus | Linnaeus, 1758 | South American rattlesnake [ref 3] | Coastal savannas of Guyana, French Guiana and Suriname |
C. d. marajoensis | Hoge, 1966 | Marajon rattlesnake [ref 4] | Known only from Marajo Island, Para State, Brazil |
C. d. maricelae | García Pérez, 1995 | Bolson arido de Lagunillas, Estado Mérida, Venezuela | |
C. d. ruruima | Hoge, 1966 | Known from the slopes of Mount Roraima and Mount Cariman-Perú in Venezuela (Bolívar). A few specimens have been recorded in Brazil (Roraima). [ref 3] | |
C. d. terrificus | (Laurenti, 1768) | Cascavel [ref 2] | Brazil south of the Amazonian forests, extreme southeastern Peru, Bolivia, Paraguay, Uruguay, northern Argentina |
C. d. trigonicus | Harris & Simmons, 1978 | Inland savannas of Guyana |
A large Neotropical rattlesnake, it grows to a length of 1.5 m (4.9 ft), and rarely to a maximum length of 1.9 m (6.2 ft). [2] It has two distinct stripes starting at the base of the head. Within the lines, the color is lighter than the stripes.
The color and pattern of the body are quite variable, most with an 18–32 dorsal with a darker diamond, and rhombic spots, 25–33 (usually 27) rows of dorsal scale in the middle of the body. The head has a dark brown bar at the top, with a dark post-orbital band. The color of the belly varies, it can be white or yellowish, with light gray spots, becoming darker towards the tail. The tail is usually gray, with dark and vague crossed bands.
The species is more active at dusk and in the early hours of the morning; it is highly alert with little warning signs before striking, but like other rattlesnakes they are seldom aggressive towards humans. [6]
The South American rattlesnake has a seasonal reproductive cycle; competition between males (for access to females) begins around the summer's end, with copulation occurring during the fall, and the birth of the young taking place the following spring/summer. [7] Reproduction is ovoviviparous, giving birth to 4–8 young. [6] In Roraima, Brazil it has been reported that the gestation lasts for 5 months, and they are capable of giving birth to up to 14 young. [8]
The diet consists mainly of rodents, likely due to the great abundance and availability of these animals throughout the year, in most areas where the snakes reside. In some regions, lizards of the Teiidae family are also part of the diet of C. durissus. [9]
Common names for the species include: South American rattlesnake, [2] tropical rattler, tropical rattlesnake, [4] neotropical rattlesnake, [10] Guiana rattlesnake (previously used for C. d. dryinus). [11] and in Spanish: víbora de cascabel, cascabel, cascabela, and also in Portuguese, cascavel. [2] In Suriname it is known as Sakasneki. [12]
Crotalus durissus is found in South America except the Andes Mountains. However, its range is discontinuous, [2] with many isolated populations in northern South America, including Colombia, Venezuela, Guyana, Suriname, French Guiana and northern Brazil. It occurs in Colombia and eastern Brazil to southeastern Peru, Bolivia, Paraguay, Uruguay, and northern Argentina (Catamarca, Córdoba, Corrientes, Chaco, Entre Rios, Formosa, La Pampa, La Rioja, Mendoza, Misiones, San Juan, San Luis, Santa Fe, Santiago del Estero and Tucumán). [3] It also occurs on some islands in the Caribbean, including Aruba. [2] The type locality given is "America." [3]
It prefers savanna and semi-arid zones. It has been reported to occur in littoral xerophilous scrub, psammophilous and halophilous littoral grassland, thorny xerophilous scrub, tropophilous deciduous and semideciduous scrub, as well as tropophilous seasonal semideciduous forest in the northwest of Venezuela. In the Chaco region of Paraguay, it is found in the drier, sandier areas. [2]
Bite symptoms are very different from those of Nearctic species [13] due to the presence of neurotoxins (crotoxin and crotamine) that cause progressive paralysis. [2] Bites from C. d. terrificus in particular can result in impaired vision or complete blindness, auditory disorders, ptosis, paralysis of the peripheral muscles, especially of the neck, which becomes so limp as to appear broken, and eventually life-threatening respiratory paralysis. The ocular disturbances are sometimes followed by permanent blindness. [13] Phospholipase A2 neurotoxins also cause damage to skeletal muscles and possibly the heart, causing general aches, pain, and tenderness throughout the body. Myoglobin released into the blood results in dark urine. Other serious complications may result from systemic disorders (incoagulable blood and general spontaneous bleeding), hypotension, and shock. [2] Hemorrhagins may be present in the venom, but any corresponding effects are completely overshadowed by the startling and serious neurotoxic symptoms. [13] Acute renal failure is considered as the main cause of death. [14] The mortality rate of cases without specific serum treatment is 72%, and 11% in cases with specific treatment. [15] The LD50 value is 0,047 mg/kg IV, 0,048 mg/kg IP and 1,4 mg/kg IM. The SC median lethal dose varies widely: 0.0478 mg / kg, 0.6 mg / kg, 0.171-0.193 mg / kg, 78 μg / kg and 74 μg / kg. The lethal dose for 60 kg humans is 18 mg, while the venom yield is 100 mg. [16] [17] [18] A study points out that the rattlesnakes in Roraima, Brazil have two types of venom, with different characteristics of individuals of the same species found in other regions, the two types of venom are known as '' yellow venom '' that attacks the nervous system, causing paralysis, and also kidney and respiratory failure, causes muscle pain and makes urine dark, and the "white venom" is hemorrhagic and causes bleeding. [8]
Crotalus is a genus of venomous 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.
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.
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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.
Crotalus simus is a venomous pit viper species found in Mexico and Central America. The specific epithet is Latin for "flat-nosed", likely because its head is blunt compared with lanceheads (Bothrops). Three subspecies are recognized, including the nominate subspecies described here.
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Crotamine is a toxin present in the venom of the South American rattlesnake. It is a 42-residue long protein containing 11 basic residues and 6 cysteines. It has also been isolated from the venom of North American prairie rattlesnake, Crotalus viridis viridis. It was first isolated and purified by Brazilian scientist José Moura Gonçalves, and later intensively studied by his group of collaborators at the Medical School of Ribeirão Preto of the University of São Paulo.
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.
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Crotalus tzabcan, the Yucatán neotropical rattlesnake, is a species of pit viper in the family Viperidae. It was previously thought to be a subspecies of Crotalus durissus, until Wüster elevated it to species status in 2005.
Crotalus durissus possui um ciclo reprodutivo sazonal com cópula ocorrendo no outono e a parturição no final no verão. Os machos competem por fêmeas receptivas.
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