Is stereo olfactory ability restricted to humans?

Question

Most animals I see around seem to have two nostrils - humans, snakes, birds, fish .. and so on. From reading online I see that 2 nostrils provide a stereo olfactory effect. This stereo effect is caused by the difference in flow of air through the nostrils. Does this stereo effect apply only to humans? Are there any animals that have a different number of nostrils? Say, more than 2, or less.

Answer 1

This mechanism applies to many animals, including humans! For example, dogs have a very keen sense of smell, and they are great at localizing the source of a scent through “stereo-olfaction.” Most animals do have 2 nostrils, for this purpose and also due to symmetry in development.