How does non-poisonous snakes kill there prey?

Pythons and boas are the most well known of the snake species that use constriction as a method to kill their prey.  This is a very powerful method used by the non-poisonous snakes like anaconda. Constrictors typically prey on large animals that can cause serious injury to the snake if they are not first incapacitated. The method used by these snakes is to tighten their body around the prey, resulting in suffocation – they do not crush their prey. The snake typically bites the prey to hold on as he quickly wraps his body and tightly coils around the prey. Each time the victim exhales a breath the snake tightens, preventing the animal from inhaling more air. Means the victim has a feeling that as and when he breaths out the coil of the snake becomes even more tight preventing the prey to breathe again. Without an air supply, the prey rapidly becomes unconscious and usually dies. The snake then inject the prey.