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[edit] Snakes
Constriction is a method used by various snake species to kill their prey. Constrictors do not have venom in their fangs to kill prey; instead, they simply squeeze them to death. The snake initially strikes at its prey and holds on, pulling the prey into its coils or, in the case of very large prey, pulling itself onto the prey. The snake will then wrap one or two coils around the prey, typically the prey's chest. Contrary to myth, the snake does not crush the prey, or even break its bones, but instead squeezes, tightening its grip when the prey exhales so that it can no longer draw in air. The snake can sense the prey's heartbeat and holds firm until the heart, deprived of oxygen, has stopped beating so that the prey will not recover and struggle while being swallowed. The snake then engulfs the prey.
Certain groups of snakes have characteristic patterns of constriction, including the number of coils they use and the orientation of the coils. Also, there is controversy about how much role restriction of circulation plays in subduing prey.
[edit] Other meanings
Constriction, the opposite of dilation or dilatation, also refers to vasoconstriction, the narrowing of blood vessels caused by vascular smooth muscle contractions.
Constriction can also refer to the act of binding a victim with rope, either as a method of torture or sexual bondage.