My nerite snail Bucky was above the water line for a little while and when he went back under I saw him pull his head in sharply 3 times and then a bubble came out his other end.
I'm really happy with my 3 nerites Bucky, Speedy and Ninja. They cleaned the tank beautifully and they are cute and fun to watch. Except Ninja who I almost never see. They may poop more than a fish will, but I vacuum regularly.