Known as the western diamondback rattlesnake, the Crotalus atrox is a species of rattlesnake found in the southwest of the United States and in northern Mexico. Among all the species of rattlesnakes, it is the most venomous as it has both hemotoxic and cytotoxic venom, which causes internal bleeding and tissue damage. Symptoms caused by the Crotalus atrox venom are abdominal pain, nausea, headache, and severe swelling followed by necrosis at site of the bite wound. So, the bite can be lethal if patient is not treated.The western diamondback rattlesnake can measure up to 1.50 m long; its head is heart-shaped and its body color is grey-brown, with creamy white lines which form diamond patterns. It feeds on mice, rats, and hare.