The largest rattlesnake in the United States is the Eastern Diamondback Rattlesnake which can grow up to eight feet long. All rattlesnakes have toxic venom that affect the circulatory and nervous systems of humans. Mojave Rattlesnakes are known to have neurotoxic venom that disrupts brain functions. Despite their highly toxic fangs, rattlesnakes rarely use them on humans. Rattlesnakes, like most snakes, will choose flight over fight unless they are cornered and have no other choice but to attack.
Water moccasins are snakes most common to the swampy areas of the southern United States.
These snakes have an aggressiveness that is more legendary than accurate. Water moccasins, also known as Cottonmouths, live around marshy areas where their main source of food of frogs, turtles and fish live in abundance. These snakes do not spend most of their time submerged in water waiting to attack unsuspecting swimmers, as many believe. Cottonmouths will flee before attacking humans. When it feels there is no escape, it will coil its body and open its mouth wide.