How do flies smell?
A fly smells mainly with its two antennae. Smell receptors on them fire when an odor lands, and the signal travels into the brain to be sorted.
A fly has no nose. It smells mainly with its two antennae, which are covered in tiny hairs, and inside each hair sit smell receptors: nerve cells that fire when the right odor molecule lands on them. A fruit fly has about 50 kinds of receptor, and each kind answers to its own set of smells. That mix of signals is how the fly tells one smell from another.
The receptors send their signal to the antennal lobe, the first stop for smells in the brain. There, all the receptors of one kind meet in the same spot, so a smell becomes a pattern of active spots. Projection neurons carry that pattern deeper, to the mushroom body, where the fly links smells to good and bad experiences.
See it in a lesson
Key terms
- Antennae
- The two feelers on a fly’s head. A fly smells with them, the way you smell with your nose.
- Smell receptors
- Nerve cells on the antennae that fire when a smell lands on them. Every smell starts here.
- Antennal lobe
- The first stop for smells inside the fly’s brain, where the smell receptors hand their signal to the projection neurons.
- Projection neurons
- Nerve cells that carry the smell signal from the antennal lobe deeper into the brain, to the mushroom body.