Todd Nicolson, of Balclutha Primary School, asks :-

How do venomous snakes get the poison in their teeth?

Jean Arnott and Alex Davies, of Massey University's School of Veterinary Science, responded.

Most poisonous snakes have enlarged teeth called fangs on their upper jaw. The Duverney's gland that produces the venom is also found in the upper jaw. Hollow fangs thus permit the snake to inject its poison into its prey. These hollow fangs can be either quite short (as in cobras, mambas, coral snakes and sea snakes) or rather long (as in rattlesnakes, African puff adders and pit vipers). The short hollow teeth are permanently erect whereas the long hollow fangs rotate to fold against the roof of the mouth so the snake can close its jaw.

There is a third group of venomous snake that has its fangs, which are not hollow, near the back of its jaw pointing towards its throat. This group includes African and Asian opisthoglyphs, some of which have a groove on the surface of their fangs that may help conduct poisons into the wound. They hold their prey (normally lizards or birds) in their mouth until they stop struggling. Then they are swallowed. The poison enters via a bite mark, hence the need to hold their prey.

Snakes that inject their poison can let go their prey and then follow its scent to find their now still meal. Experiments have shown that vipers can tell the difference between scent left by a bitten mouse from that of an untouched mouse. What an amazing sense of smell.