According to popular knowledge, venomous snakes are in the minority. Most kill their prey through other means. The pythons and boas, for example, squeeze their prey to death, constricting them in powerful coils until they can no longer breathe.
But that doesn’t mean they lack venom.
The ‘venom’ glands of these constrictors mostly produce lubricating mucus, which helps the snakes to swallow prey easily. But Bryan Fry from the University of Queensland has found that the glands still produce small amounts of venom proteins. So do the equivalent glands of iguanian lizards—the group that includes iguanas, anoles and chameleons.
These snakes and lizards are unlikely to be using their venom to subdue prey or to defend themselves, but they clearly still make the stuff. Their toxins are the equivalent of a kiwi’s wing or the sightless eyes of blind cavefish—defunct remnants of a functional past…