They include anacondas , pythons , and boa constrictors , which are all non-venomous constrictors .
The largest living snakes in the world , measured either by length or by weight , are various members of the boidae and pythonidae families .
families include anacondas , pythons , and boa constrictors , which are all non-venomous constrictors .
The largest living snakes in the world , measured either by length or by weight , are various members of the boidae and pythonidae families .