How do animals use their sense of smell to find water in dry environments?

[Gerinski]

If I'm not wrong, several species of animals, for example those living in dry areas of Africa, have the ability to find water many kilometers away. They may be in a dry area with no water around, and say, the nearest small dwell 20 Kms away in North direction, and somehow they can orientate themselves and walk North until finding the water rather than taking some other random direction which would lead them to dead by dehydration.
Is there any scientific studies / evidence for which mechanisms do they use to achieve that? for relatively nearby water sources I guess that wind might carry some moisture molecules to their nose, but I doubt that this can be the case for distant water sources.

 

[UltrafastPED]

They do smell it ... some noses are more sensitive than others. Human noses are about at the bottom of the list.

Here is a nice history of camels: http://nabataea.net/camel.html

But it doesn't explain the biochemistry of the camel's nose!

 

[Gerinski]

Thanks. Are you quite sure of that? so if the wind blows in the wrong direction, they will be unable to find the water?
(incidentally, I wonder if 'smell' is the right word when referring to water?)

 

[UltrafastPED]

As an old sailor I can assure you that people can smell water too ... there is always something in the air, be it salt or decaying seaweed on the beach.

Of course you are correct: if the wind is blowing in the wrong direction your sense of smell won't be able to detect anything. And all water has stuff in it - you would have to do a research study to determine what it is exactly that the camels smell. But they do go for the water - this selectivity is required for their survival in their native habitats.

 

[jim mcnamara]

Ungulates (mostly what you think of when thinking "African mammals on the savannah") have a huge relative OOS - (olfactory organ size) - for the size of the skull compared to humans. This is usually offered as an explanation of why most animals "smell" more effectively than humans, and great apes. Our OOS is small.
http://rspb.royalsocietypublishing.org/content/272/1566/957.full

In domestic dog breeds the OSS varies depending on the what we would "nose length". Dog breeds like blood hound and basset hounds have longer noses, larger OOS. Not surprising is the fact the long wide nose breeds of dog do better in the scent ability department. Search and rescue teams prefer these type of dogs, when trailing lost people, for example.

see: http://en.wikipedia.org/wiki/Bloodhound#Scenting_ability

PS: ungulates == antelope, deer, bison, eland, zebra; so you do not have to look it up.