Many experts believe the Mojave, or Mohave, rattlesnake to be the most venomous snake in North America. Besides living in the Mojave Desert, from which it gets its name, the rattlesnake is found primarily in regions of extreme western Texas, southern Nevada, and south to central Mexico. Herpetologists generally classify it as a medium-sized rattlesnake because it is between two and three feet (about 61 to 91 cm) long. Scientifically, it is known as Crotalus scutulatus, but people often mistake it for the western diamondback, or Crotalus atrox, because both have the diamond markings on their backs. Some people mistakenly call the snake the Mojave green.
On the back of the Mojave rattlesnake are well-defined diamonds edged with a lighter color. The diamonds on the rattlesnake fade away on the last third of the snake's body, whereas the western diamondback's diamonds continue all the way to the tail. At the tail, the Mojave rattlesnake's rings contrast light and dark with the lighter rings being larger; the diamondback has larger, thick black rings and thin light ones. The Mojave rattlesnakes usually are brown or yellowish brown in lower elevations and greenish gray or olive green in the high regions. The snake also has a postocular stripe that extends down to just above the mouth; the diamondback's stripe intersects at the corner of its mouth.
Adult California ground squirrels are immune to their toxin, but the Mojave rattlesnakes eat young squirrels, lizards, and other rodents, including the Kangaroo rat. Mojave rattlesnakes are nocturnal hunters, although they often hunt on cooler, overcast days. During the day, they hide in crevices or rodent burrows. During July to September, the Mojave rattlesnake gives live birth to between four and 20 young that typically measure about nine to 11 inches (23 to 28 cm) long. The young snakes are more dangerous because they have not grown a rattle to warn people away and they usually inject more venom.
Another snake that the Mojave rattlesnake resembles is the Mojave sidewinder rattlesnake, which also inhabits the Mojave Desert. The sidewinder has a horn-like scale over each eye and moves in the distinctive sidewinding movement. The sidewinder also buries itself in the sand with only its head above ground to hunt prey. The Mojave rattlesnake does not exhibit either of these behaviors. Other characteristics that can help to identify it as a viper are its large, triangular head and long, movable fangs.
The Mojave rattlesnake's toxin — called the Mojave toxin — attacks the victim's nervous system with a neurotoxin and the blood system with a hemotoxin. Some experts say that this rattlesnake's venom is 16 times as strong as the Mojave sidewinder rattlesnake. The snake controls the amount of venom it excretes. The bite might be deceptive as it often is not as painful as other snakebites. Experts advise against handling dead snakes because of a reflexive reaction that can cause the snake to bite and inject venom.