''Crotalus durissus'', known as the South American rattlesnake, tropical rattlesnake,Mehrtens JM. 1987. Living Snakes of the World in Color. New York: Sterling Publishers. 480 pp. and by other names, is a highly

venomous 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 sti ...

pit viper The Crotalinae, commonly known as pit vipers,Mehrtens JM (1987). ''Living Snakes of the World in Color''. New York: Sterling Publishers. 480 pp. . or pit adders, are a subfamily (biology), subfamily of Viperidae, vipers found in Asia and the ...

species 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. It is the basic unit of Taxonomy (biology), ...

found in

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

. It is the most widely distributed member of its genus. Currently, seven

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are recognized.

Taxonomy

The Guiana rattlesnake, previously recognized as ''C. d. dryinus'', 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''. 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

Description

A large

Neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...

rattlesnake, it grows to a length of , and rarely to a maximum length of . 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.

Behaviour

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.

Reproduction

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. Reproduction is

ovoviviparous Ovoviviparity, ovovivipary, ovivipary, or aplacental viviparity is a "bridging" form of reproduction between egg-laying oviparity, oviparous and live-bearing viviparity, viviparous reproduction. Ovoviviparous animals possess embryos that develo ...

, giving birth to four to eight young. In Roraima, Brazil it has been reported that the gestation lasts for five months, and they are capable of giving birth to up to 14 young.

Diet

The diet consists mainly of

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

, 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 Lizard is the common name used for all squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The ...

of the

Teiidae Teiidae is a family of lacertoidean lizards native to the Americas. Members of this family are generally known as whiptails or racerunners; however, tegus also belong to this family. Teiidae is sister to the Gymnophthalmidae, Gymnopthalmidae, and ...

family are also part of the diet of ''C. durissus''.

Common names

Common names for the species include: South American rattlesnake, tropical rattler, tropical rattlesnake, neotropical rattlesnake,U.S. Navy. 1991. Poisonous Snakes of the World. US Govt. New York: Dover Publications Inc. 203 pp. Guiana rattlesnake (previously used for ''C. d. dryinus'').Brown JH. 1973. Toxicology and Pharmacology of Venoms from Poisonous Snakes. Springfield, Illinois: Charles C. Thomas. 184 pp. LCCCN 73-229. and in Spanish: ''víbora de cascabel, cascabel, cascabela'', and also in Portuguese, ''cascavel''. In Suriname it is known as Sakasneki.

Geographic range

''Crotalus durissus'' is found in South America except the Andes Mountains. However, its range is discontinuous, with many isolated populations in northern South America, including

Colombia Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

Guyana Guyana, officially the Co-operative Republic of Guyana, is a country on the northern coast of South America, part of the historic British West Indies. entry "Guyana" Georgetown, Guyana, Georgetown is the capital of Guyana and is also the co ...

Suriname Suriname, officially the Republic of Suriname, is a country in northern South America, also considered as part of the Caribbean and the West Indies. It is a developing country with a Human Development Index, high level of human development; i ...

French Guiana French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...

and northern

Brazil Brazil, officially the Federative Republic of Brazil, is the largest country in South America. It is the world's List of countries and dependencies by area, fifth-largest country by area and the List of countries and dependencies by population ...

. It occurs in Colombia and eastern Brazil to southeastern

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Bolivia Bolivia, officially the Plurinational State of Bolivia, is a landlocked country located in central South America. The country features diverse geography, including vast Amazonian plains, tropical lowlands, mountains, the Gran Chaco Province, w ...

Paraguay Paraguay, officially the Republic of Paraguay, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

, and northern

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

( Catamarca, Córdoba, Corrientes, Chaco, Entre Rios,

Formosa Taiwan, officially the Republic of China (ROC), is a country in East Asia. The island of Taiwan, formerly known to Westerners as Formosa, has an area of and makes up 99% of the land under ROC control. It lies about across the Taiwan Strait f ...

, La Pampa,

La Rioja La Rioja () is an autonomous communities in Spain, autonomous community and provinces of Spain, province in Spain, in the north of the Iberian Peninsula. Its capital is Logroño. Other List of municipalities in La Rioja, cities and towns in the ...

, Mendoza, Misiones,

San Juan San Juan, Spanish for Saint John (disambiguation), Saint John, most commonly refers to: * San Juan, Puerto Rico * San Juan, Argentina * San Juan, Metro Manila, a highly urbanized city in the Philippines San Juan may also refer to: Places Arge ...

, San Luis, Santa Fe,

Santiago del Estero Santiago del Estero (, Spanish for ''Saint-James-Upon-The-Lagoon'') is the capital of Santiago del Estero Province in northern Argentina. It has a population of 252,192 inhabitants, () making it the twelfth largest city in the country, with a sur ...

and Tucumán). It also occurs on some islands in the

Caribbean The Caribbean ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...

, including

Aruba Aruba, officially the Country of Aruba, is a constituent island country within the Kingdom of the Netherlands, in the southern Caribbean Sea north of the Venezuelan peninsula of Paraguaná Peninsula, Paraguaná and northwest of Curaçao. In 19 ...

. The type locality given is "America."

Habitat

It prefers

savanna A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

and

semi-arid A semi-arid climate, semi-desert climate, or steppe climate is a aridity, dry climate sub-type. It is located on regions that receive precipitation below Evapotranspiration#Potential evapotranspiration, potential evapotranspiration, but not as l ...

zones. It has been reported to occur in

littoral The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely i ...

xerophilous scrub, psammophilous and halophilous littoral

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

, thorny xerophilous scrub, tropophilous

deciduous In the fields of horticulture and botany, the term deciduous () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed Leaf, leaves, usually in the autumn; to the shedding of petals, aft ...

and semideciduous scrub, as well as tropophilous seasonal semideciduous forest in the northwest of

. In the Chaco region of

, it is found in the drier, sandier areas.

Venom

Bite symptoms are very different from those of

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America ...

species due to the presence of

neurotoxin Neurotoxins are toxins that are destructive to nervous tissue, nerve tissue (causing neurotoxicity). Neurotoxins are an extensive class of exogenous chemical neurological insult (medical), insultsSpencer 2000 that can adversely affect function ...

s (crotoxin and crotamine) that cause progressive paralysis. 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. Phospholipase A₂ neurotoxins also cause damage to skeletal muscles and possibly the heart, causing general aches, pain, and tenderness throughout the body.

Myoglobin Myoglobin (symbol Mb or MB) is an iron- and oxygen-binding protein found in the cardiac and skeletal muscle, skeletal Muscle, muscle tissue of vertebrates in general and in almost all mammals. Myoglobin is distantly related to hemoglobin. Compar ...

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. Hemorrhagins may be present in the venom, but any corresponding effects are completely overshadowed by the startling and serious neurotoxic symptoms. Acute renal failure is considered as the main cause of death. The mortality rate of cases without specific serum treatment is 72%, and 11% in cases with specific treatment. The

LD50 In toxicology, the median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 is a toxic unit that measures the lethal dose of a given substance. The value of LD50 for a substance is the dose requ ...

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. 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.

References

External links

* * {{Taxonbar, from=Q854864 durissus Snakes of the Caribbean Snakes of Aruba Snakes of Brazil Reptiles of Bolivia Reptiles of Argentina Reptiles of Colombia Reptiles of French Guiana Reptiles of Guyana Reptiles of Paraguay Reptiles of Peru Reptiles of Suriname Reptiles of Uruguay Reptiles of Venezuela Reptiles described in 1758 Taxa named by Carl Linnaeus