The 36 known species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from southern Alberta, Saskatchewan, and southern British Columbia in Canada to central Argentina.

Most species live near open, rocky areas, but rattlesnakes can be found in almost every type of habitat capable of supporting terrestrial ectothermic vertebrates, including prairies, marshes, deserts, and forests.

Rattlesnakes are born with fully functioning fangs and venom, and are capable of killing prey at birth.

The venom is hemotoxic, destroying tissue, causing necrosis and coagulopathy (disrupted blood clotting). In the U.S., the tiger rattlesnake (C. tigris) and some varieties of the Mojave rattlesnake (C. scutulatus) also have a presynaptic neurotoxic venom component known as Mojave type A toxin, which can cause severe paralysis.

The muscles that cause the rattle to shake are some of the fastest known, firing 50 times per second on average, for up to three hours.

Like other snakes, rattlers smell using the tip of their tongue, and a forked tongue allows them to sense from which direction a smell is coming.

According to Guinness World Records, the worlds heaviest venomous snake was a 7 foot 9 inch eastern diamondback rattlesnake (Crotalus adamanteus) that weighed in at a monstrous 34 lbs (15 kg).

It's a myth that baby rattlesnakes release more venom than adults. In fact, adult snakes have much bigger venom sacs and can deliver far greater volumes of venom than babies, even if they only inject a small percentage of the total volume available.

In a 2007 study, western diamondback rattlers (Crotalus atrox) survived nearly two years without food by lowering their standard metabolic rates by up to 72 percent.

Because of its unique method of locomotion, known as "sidewinding," the sidewinder (Crotalus cerastes) can reach speeds of up to 18 mph (29 km/h), faster than any other species of rattlesnake.