How do moles smell underwater?

Blowing Bubbles

I was pleased to see the mention of the star-nosed mole in Nick Richardson’s review of Ned Beauman’s latest novel (LRB, 17 July). Richardson informs us that this marvellous creature ‘can smell underwater’. True, but not thanks to the ‘nose’ that gives it its name. The 22 fleshy appendages that protrude from the mole’s face are not an olfactory organ at all, but a skin surface containing more than 100,000 sensory neurons – it’s the most acute touch organ of any mammal on the planet and about six times more sensitive than the human hand. In order to ‘smell’ underwater – a phenomenon long thought impossible in mammals – the mole exhales air bubbles over objects then reinhales them, allowing odorant molecules in the bubbles to pass over the olfactory receptors.

Sarah Murray

The link is here, pointer from Hugo Lindgren.


I am 'impressed' that all the 'touch' surfaces of all mammals on the planet have been studied in sufficient detail to make this claim. Do you have the citation? Otherwise, I'd have to conclude it's speculation and hyperbole. I'm thinking that's not consistent with 'truth telling'.... Oh, also: is the human 'hand' our most sensitive sensory surface? I would have thought there are several better candidates including the human finger tip, nose, face, tongue, and possibly some surfaces in the genital area...

It looks like the authors copied from here and removed the "probably".

Pedantic much?

No, quite right. A sweeping claim was made; "what's the evidence for it?" is always a legit question. It should be asked more often.

If I said that Usain Bolt is the fastest man alive, would that be a sweeping statement requiring extraordinary proof or would I need a page of legal disclaimers?

The quote mentions the approximate number of sensory neurons. A quick lookup of Olfaction shows that the sense of smell for mammals has been well studied. There are comparisons between bloodhound sense of smell and humans.

The quote does not say that the human hand is the most sensitive touch organ. It only gives the mole's number of neurons relative to the hand which, if Im not mistaken, includes the fingertips.

Sit back and enjoy the article.

Jack Paul above shows how wise the question was, and thereby how wrong you are. Well done, Li Zhi.

"A quick lookup of Olfaction shows that the sense of smell for mammals has been well studied" (snip)

Except that there is no one theory to explain how it actually works. Luca Turin:

'Well studied': Rookie error.

Like a wet mole?

My parents once won a radio contest with this riddle:

How do you stop a fish from smelling?

Cut off its nose.

Just looked at pictures of the star nosed mole. Terrifying.


Damn you (a little) for beating me to that.

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