They aim to spot the molecules thought to emit the scent.

Ewes have estrus cycles about every 17 days, during which they emit a scent and indicate readiness through physical displays towards rams.

During breeding season the female boa will emit a scent from her cloaca to attract males, who may then wrestle for the right to breed with her.

To attract females, the male emits a scent rather similar to pineapple.

To pollinate, the flowers attract flies by emitting a scent similar to that of carrion.