In the winter their metabolisms slow down, and they use up body fat which has been stored up during the warmer months of the year. Most venomous snakes grab their prey by striking suddenly and biting while they inject venom into the victim. Some species will often strike three or four times. The toxins produced by the venomous snakes act to paralyse the victim, so that it dies or is unable to move before the snake tries to eat it. These toxins also assist the snake's digestive processes, beginning by breaking down the victim's blood and other tissues.
Pythons have no venom and use their strong bodies to immobilise their victims.
Having first grabbed the prey with its mouth, a python wraps its body coils tightly around the victim. As the coils are progressively tightened, the prey is suffocated. Other snakes grab their prey in their mouth and start swallowing immediately so that the animal is eaten alive. The teeth in these snakes are arranged so as to resist escape of an animal once grabbed in the mouth. Sometimes both venom and constriction are used to kill and hold the prey.