Re: Why do snakes have nostrils?

Dear Evan:

You are correct that snakes use their tongue assist with smell. Actually the snake's organ of smell is Jacobson's organ in the roof of the mouth. The tongue with its constant flickering action brings odorous particles to Jacobson's organ, the forked tip presumably bringing the scent to both openings.

One of my references states that snakes also smell with their nostrils. This is probably true since there is a connection from the nasal cavity to the mouth.

The main purpose for the nostrils, however, is for respiration. Most of the time the snake breaths with its mouth shut. Thus the nostrils are the main route of air to the lungs (actually most snakes only have one functioning lung, the right one, which is mostly just an airsac). If you ever see a snake with a respiratory infection, you will note the abnormal open-mouth breathing.

Hope this helps.