Rattlesnakes

Rattlesnakes are venomous snakes in the subfamily Crotalinae, comprising the genera Crotalus and Sistrurus. They are native to the Americas, from southern Canada to northern Argentina, with the greatest species diversity in North and Central America and arid regions. A defining feature is the rattle at the tail, formed by stacked keratinous segments that are added after molts. When threatened or excited, many species shake the tail to create a warning buzz. Rattlesnakes possess heat-sensing pits between the eyes and nostrils that help detect warm-blooded prey.

Diet and hunting vary by species but generally include small mammals, birds, lizards, and occasionally amphibians. They rely on venom to immobilize or pre-digest prey and strike with long, retractable fangs that fold against the roof of the mouth when not in use. Venom composition ranges among species, often containing proteolytic enzymes and, in some cases, neurotoxic components, along with hemorrhagic effects. Envenomation poses a serious medical risk to humans and requires prompt treatment.

Reproduction is typically ovoviviparous or viviparous, with most rattlesnakes giving birth to live young after a period of gestation of several months. Litters can vary in size and the newborns are usually independent soon after birth.

Conservation status varies by species and region. While some rattlesnakes are widespread and not threatened, others face habitat loss, persecution, road mortality, and declines in prey. They play an important ecological role in controlling small vertebrate populations and are subjects of venom research that has led to medical advances.