Crotalus

Crotalus is a genus of venomous snakes in the family Viperidae, subfamily Crotalinae. Commonly known as rattlesnakes, they are native to the Americas, ranging from southern Canada to northern Argentina. The genus comprises about 25 to 30 recognized species and multiple subspecies, with taxonomy varying by authority. A defining feature is the rattle at the tail, formed by keratinous segments that grow with each molt and are used as a warning when the snake vibrates the tail.

Crotalus species are characterized by a triangular head, a stout body, and heat-sensing pits between the eyes and nostrils. They possess solenoglyphous fangs that fold back against the roof of the mouth to deliver venom. The venom is primarily hemotoxic, causing tissue destruction, coagulopathy, and systemic effects, though venom composition can vary among species. Envenomation requires prompt medical attention and species-appropriate antivenom.

Most Crotalus species are ovoviviparous, giving birth to live young after a gestation of several months; some lay eggs in warmer climates. Litters range in size and the young are often ready to fend for themselves shortly after birth. Reproduction and growth rates vary with species and environment.

Ecology and behavior: rattlesnakes are ambush predators that feed on small mammals, birds, lizards, and other vertebrates. They are generally inactive during extreme heat or cold and may be diurnal or nocturnal depending on species and weather. They rely on camouflage, patience, and venomous strike to capture prey, and may hiss or rattle when threatened.

Conservation and taxonomy: habitat loss, persecution, and over-collection threaten some populations, while others remain widespread. The number of recognized species is subject to revision as new data emerge. Notable species include Crotalus adamanteus (eastern diamondback), C. atrox (western diamondback), C. durissus (South American rattlesnake), and C. cerastes (sidewinder).