Hi,
I've done some reading about the subject and couldnt reach a conclusion ...
At first I thought its only common for mammals, but then I read that Iguanas sneeze for example.

So, in case its only related to mammals only, and assuming more animal families do sneeze - is there any physical character that resutls in sneezing ? Why some animals do sneeze and other dont ?

Thanks !

First of all, only tetrapods need to sneeze. Sneezing is a way of clearing the respiratory tract of dust, mucous and other obstructions - it is triggered by nasal irritation. Animals with gills, spiracles or other methods of obtaining oxygen don't 'sneeze' as such (although they will have other methods of keeping their respiratory apparatus clear of obstructions).

Whales are one type of tetrapod that probably doesn't sneeze (suddenly losing a lungful of air whilst deep underwater might prove  disadvantageous) - they have a very different configuration of their nasal passages to prevent water (or other irritants) from entering and they have a conscious control over expelling large amounts of air rapidly - I suppose this could be considered controlled sneezing. Come to think of it, I expect that most aquatic tetrapods probably don't sneeze.

However, I think it likely that all terrestrial tetrapods probably have some kind of sneezing mechanism.

A very good observation was made about this topic by Rupert Clayton:

I think Paolo Viscardi's answer to "Do all animals sneeze?" ( http://www.askabiologist.org.uk/answers … hp?id=3071 ) could benefit from a short discussion of hagfish.

Apparently hagfish also "sneeze" to clear their single nostril of the copious slime they produce. (See http://blogs.smithsonianmag.com/science … t-hagfish/ and http://www.ucmp.berkeley.edu/vertebrate … yxini.html ).

As hagfish are likely basal to vertebrates, one explanation could be that sneezing is an extremely ancient behavior. Of course, the alternative is that a hagfish "sneeze" and a mammalian sneeze are superficially similar behaviors with different origins. It would be interesting to know how many times sneezing appears to have evolved, and whether any animals have lost the behavior (e.g. marine mammals).