Why do they have nostrils?
Well, I couldn’t find a page that directly talked about goldfish nostrils, but at this site about the closely related koi, http://members.iinet.net.au/~tsf/koi/koi_anatomy.html, it says
How can you smell underwater? I can’t smell unerwater. I get all sneezy and coughy and really hacks of the fish.
Scent particles float through the water, and when they wash over the scent organ in the goldfish nostrils, the fish smells. You can’t smell underwater because your nostrils, unlike goldfish nostrils, are connected to lungs. Does anyone else get a kick out the phrase “goldfish nostrils”?
Oh, and since I never get to say it, wouldn’t Goldfish Nostrils be a great band name?
Perhaps because you’re meant to be breathing air?
Fish don’t have nostrils. They have nares. Each nare has two openings separated by a little flap. Cilia push water in one opening and out the other, past the sensory cells within the nare. Fish do use them for smelling, but of course not for breathing.
Obviously our sinuses are better equiped for dealing with airborne scent particles than those in water. But water carries stuff better. I suspect that we really could smell waterborn substances with our nostrils (or more acurately with the sensory organs in our sinuses) if we could get past the nasty sensation of having water in there. The molecules that we normally smell probably have to be dissolved in the fluids excreted by our mucous membranes in order to be sensed. I would guess that they would move over from water just as well as from the air, but no real proof.
Fishhead
I saw some of that in the bathroom…
Fishead This is the first new thing I’ve learned about fish anatomy since I was a tyke. And it makes me want to go right out and find a fish to inspect. Another point for Science On The March.