Octopus Smell: Where Are Their Noses and How Do They Smell?

Anatomy of Olfaction

Octopuses lack a nose. Instead, they have two olfactory organs (osphradia) located in the mantle cavity, near the gills. Each connects to a small external opening (sometimes called a “nostril”) on the head.

Mechanism

• Water flows over the olfactory epithelium (cilia on sensory neurons).
• Chemoreceptors detect dissolved odorants (amino acids, amines, peptides).
• Signals transmitted via olfactory lobe to brain (large optic lobes, but also well-developed olfactory lobes).

Capabilities

• Highly sensitive: detect prey (crabs, fish) at low concentrations.
• Discriminate individual conspecifics, predators, mates.
• Learn and remember odors (associative learning demonstrated in lab).
• Use smell for navigation, den selection, and social recognition.

Comparison

Unlike vertebrates, cephalopod olfaction is water-based (no airborne smell). The “nose” is a chemosensory pit, not a respiratory passage.