Study
Underwater "sniffing" by semi-aquatic mammals
Catania, Kenneth C.
Nature, 2006
Filmed star-nosed moles and water shrews foraging underwater at high speed, recording the exhalation and re-inhalation of air bubbles against the substrate and against scented and unscented targets, and tested trail-following performance with the behaviour prevented.
- Studied in
- Condylura cristata, Sorex palustris
- Sample size
- star-nosed moles and water shrews filmed foraging underwater
The animals exhaled air bubbles onto objects and re-inhaled them at rates of up to about ten times a second, and followed scent trails underwater successfully; performance dropped when bubble behaviour was prevented.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Semi-aquatic mammals smell underwater by using exhaled air bubbles to carry odour molecules from an object back into the nose.
How NatureHQ reads it
Included because it demolishes a piece of received wisdom that sounds like physics: mammals cannot smell underwater, because olfaction requires air. They can, by bringing the air with them. It is also a good illustration of why high-speed film changed sensory biology — at normal speed the behaviour looks like nothing at all, and the whole phenomenon is invisible without the frame rate.
- Two species, both with unusual foraging ecology; the behaviour is not general to mammals.
- Laboratory tanks rather than natural burrow and stream conditions.
- Establishes that odour is transferred; how much information the animal extracts is not quantified.
Filming a mole blowing bubbles at things underwater
Mammals are supposed to be unable to smell underwater, because smelling requires air. So how does a semi-aquatic mole follow a scent trail in a stream?
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Smell, and how far it really works
Smelling needs air, so a star-nosed mole takes air with it: it blows a bubble onto whatever it wants to smell and breathes it back in, about ten times a second.
Animal senses
The star-nosed mole examines the world by touch through an organ built like an eye: a high-resolution region it aims at things, rapid movements to bring targets into it, and a huge share of its brain.
Published by: Nature PortfolioPublished in a Nature Portfolio journal.
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-02.