Ofaction, a sense of smell, in frogs is mainly used
as a homing tool or recognising breeding areas, but
not often for detecting food.
Many frogs can sense chemical changes in the air, not
just from the nostril but from molecules collected on
their eyes and skin. Many tadpoles use picking up chemical
'scents' to detect predators and food. And learning
the chemical smell of the pool they were born in, to
return to later as frogs to breed.
A frogs nostrils are primarily for breathing through
rather than smell as they breath with their mouths shut.