Pencil Shavings

Thursday, August 10, 2006

Why is bird poop white?

For Smole, the ever curious one.

Unlike mammals, birds don't urinate. Their kidneys extract nitrogenous wastes from the bloodstream, but instead of excreting it as urea dissolved in urine as we do, they excrete it in the form of uric acid. Uric acid has a very low solubility in water, so it emerges as a white paste. This material, as well as the output of the intestines, emerges from the bird's cloaca. The cloaca is a multi-purpose hole for birds: their wastes come out of it, they have sex by putting their cloacas together, and females lay eggs out of it.

Scoop on Poop


I think that multi-purpose hole sounds a bit dodgey if you ask me.

5 comments:

Anonymous said...

whoah cloaca! thanks for the infobite :) very very interesting. ok, now why are some eggs white and some brown?

Renohtaram said...

hmmm...it'll be rather disturbing to know if egg color is affected by whatever else comes out of the cloaca! ;)

mis_nomer said...

Get this, turtles breathe through their cloaca as well!

Anonymous said...

Do turtles breathe through the cloaca?? I kept terrapins before, and I am quite sure they breathed through their cute little noses on their faces (I could feel air moving in and out of there)

mis_nomer said...

Some turtles breathe through the cloaca when submerged, but not all. Check out this article from the straight dope. It's quite funny. :) So I think you're right about your terrapin...