Bothrops jararaca — known as the jararaca or yarara — is a species of a highly venomous pit viper endemic to South America in southern Brazil, Paraguay, and northern Argentina. The specific name, jararaca, is derived from the Tupi words yarará and ca, which mean "large snake". Within its geographic range, it is often abundant and is an important cause of snakebite. No subspecies are currently recognized.
The drugs known as angiotensin converting enzyme (ACE) inhibitors, used for the treatment of hypertension and some types of congestive heart failure, were developed from a peptide found in the venom of this species.
The Jararaca is a highly venomous pit viper that occurs in South America. Its color pattern is extremely variable, consisting of a dorsal ground color that may be tan, brown, gray, yellow, olive, or almost maroon. Midbody, this color is usually somewhat lighter than the head, anterior, and posterior. The dorsal ground color is overlaid with a series of pale-edged, dark brown subtriangular or trapezoidal markings on either side of the body. These marking may be situated opposite each other, or partially or completely juxtaposed; most specimens have a pattern with all three variations. In juveniles, the tip of the tail is white. The head of the jararaca has a prominent dark brown stripe that runs from behind the eye, on either side of the head, back to the angle of the mouth. Dorsally, this stripe is bordered by a distinct pale area. The tongue is black, and the iris is gold to greenish-gold with slightly darker reticulations.
The jararaca is found in southern Brazil, northeastern Paraguay, and northern Argentina (Misiones). Its lives mainly in the dense tropical perennial forests in the Atlantic Forest, and can also be found in thickets, savannas, semitropical highland forests, as well as in cultivated fields with close vegetable openings.
The jararaca is an aggressive terrestrial snake that spends most of its time on the ground. Juveniles, however, are more arboreal and can often be found in trees. These solitary snakes usually hunt at night; during the day they are found in foliage, in places at higher altitudes, with a more significant reduction in activities during the colder months, while the peak of activity is more frequently observed during the warmer months. They are ambush predators and equipped with good camouflage. Juveniles use caudal bait to attract prey, making movements with the tip of the tail whose coloring is white; the tip of the juvenile's tail is very similar to an insect larva, and may thus attracting prey.
The jararaca has a carnivorous diet. Juveniles feed mainly on frogs and arthropods, while adults eat various mammals, especially rodents.
The jararaca is a polygynous breeder, meaning that males of this species mate with more than one female, and there are also fights between males for the female. The breeding season takes place between April and May. Females give birth in February-April, on average, producing 10-14 young per season. The gestation period typically lasts 240-300 days. The young are independent at birth and are believed to reach reproductive maturity at 2 years of age.
There are no major threats to the jararaca at present. However, it is often hunted and persecuted by people, mainly because of fear.
According to IUCN, the jararaca is common throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List.
The jararaca plays a useful role in the ecosystem it lives in. It consumes a wide variety of rodents thus helping control populations of agricultural pests and in turn, this snake is a food source to larger animals and birds of prey.
