Some snakes eat frogs, other snakes, fish, or snails. Many snakes eat rodents. They capture their prey by three methods. The first is the grab and swallow method, employed by a wide variety of snakes, including water snakes. Snakes using this technique often swallow their prey alive. Snakes also kill by constriction, which is the second method. The boa constrictor, the rat snake, and king snakes are some snakes that kill by constriction. These snakes strike at their prey and subdue it by wrapping their coils around it. The prey is not crushed, but suffocated to death. Once the prey is dead, the snake begins to swallow it. Venomous snakes use the third method. They kill their prey by injecting it with venom. The venom either kills the prey immediately, or paralyses it, so that the snake can move in for the kill.