That is not what a yawn is forthat is what breathing is for. And fish do yawn, everything with a backbone does, except for giraffes (special adaptations to their respiratory system).
Nobody knows what yawning is for really (as in primary function), though there is some evidence supporting the notion that yawning improves vigilance. It might do this by cooling blood going to the brain by drawing cooler air over the larynx which is fully aducted during a yawn: greater surface area and cooling. This might be different for fish, but they do yawn, honest.
There is also the social yawn, but I won't bore you with that :-)
(Nobody knows what yawning is for really (as in primary function), though there is some evidence supporting the notion that yawning improves vigilance. It might do this by cooling blood going to the brain by drawing cooler air over the larynx which is fully aducted during a yawn: greater surface area and cooling. This might be different for fish, but they do yawn, honest.
There is also the social yawn, but I won't bore you with that :-)
Hellzapoppin,
Mon 5 Oct 2009, 14:21,
archived)