What Is the Biggest Rattlesnake?

Rattlesnakes are members of the Crotalus genus of pit vipers. Considered the most recently evolved genus of venomous snakes, 32 known species and more than 60 subspecies of rattlesnakes are currently recognized. They are indigenous to the western hemisphere, appearing primarily in North America. Of the recognized species, diamonds or diamondbacks are the largest, so named for the characteristic diamond-shaped markings along the length of the snakes’ body. Specifically, eastern diamondbacks are the biggest rattlesnake species, growing as long as 8 feet (2.4 meters) and weighing as much as 10 pounds (4.5 kilograms.)

Eastern diamondback rattlesnakes, also known as southeastern diamondbacks, southern woodland rattlers, or Florida diamondbacks, belong to the Crotalus adamanteus species. Characteristics include larger, wider heads than most pit vipers, with noticeably visible pits — an organ resembling nostrils on either side of the snake’s head. Pits are used for hunting, allowing rattlers to identify and locate prey based on body heat. The name diamondback stems from the brown diamond-shaped markings along the snake’s body, outlined in pale to bright yellow scales. Although eastern diamondbacks are the biggest rattlesnake to feature such markings, other diamondbacks have similar patterns in different colors and levels of contrast.

All diamondbacks, including the eastern diamondback, have evolved to fit perfectly into the specific ecological needs of each species’ natural habitat, maintaining size and eating habits as appropriate. For example, the red diamondback rattlesnake is the biggest rattlesnake species in the San Diego, California area, surviving on mammals and amphibians native to the region. Alternatively, eastern diamondbacks are indigenous to the southeastern United States and feed exclusively on mammals such as rabbits and squirrels. More abundant and larger prey have contributed to the eastern diamondback’s evolution and place as the biggest rattlesnake of all Crotalus species.

In terms of habitats, eastern diamondbacks will occupy abandoned burrows, holes left by fallen trees, and other covered areas where nests can be protected. Preferring drier habitats, eastern diamondbacks typically avoid nesting in immediate areas surrounding lakes, streams, or swamps, but frequent these areas to hunt. Some have even been known to swim across bodies of water to reach preferred hunting grounds. Like most rattlesnakes, diamondbacks prefer thick vegetation when hunting, to better aid ambushing prey.

Unlike other snakes, diamondbacks do not lay eggs in the nest, instead giving birth to live young once every two to three years. Known as ovoviviparous snakes, diamondbacks mate in spring or fall, with females carrying eggs internally for a few months before giving birth to several young. Within hours, young rattlers leave the nest to pursue prey and establish a separate domicile. It can take several years for a young eastern diamondback to reach its full weight and length.