|Hi!! Do birds excrete urine? I really don't know
if they do and me and my friend were pondering
this the other day!! THanks so much, have a great
day!! :) :)
|Question Date: 2005-04-02|
Birds excrete that white pasty stuff instead of
separately urinating and defecating like mammals
do. So they don't exactly urinate, but they do
something like it. All animals have to get rid of
the nitrogen that is left over after breaking down
proteins. Mammals turn it into urea and urinate
it out. Birds and reptiles turn it into uric
Birds have a chamber called a cloaca
where digestive wastes, uric acid, and eggs or
sperm go before leaving the body. While the uric
acid is in the cloaca, birds can absorb some of
the water back. This helps them to conserve
water. Some sea birds can even drink sea water
and excrete the extra salt out of glands near
Why do you think birds need to
avoid having a full bladder? Think about the
costs of flight.
Birds, like all animals, have to get rid of their
nitrogenous wastes somehow.When animals digest
proteins and other nitrogen-containing compounds,
one of the waste products is ammonia, which is
toxic. Ammonia is so toxic, in fact, that it has
to be kept pretty dilute in order to protect the
animal. So the simplest solution is to excrete
lots and lots of very dilute urine with ammonia in
it. This is what lots of aquatic animals do,
since they don't have to conserve water. Mammals,
for the most part, don't have access to an
unlimited supply of water, so don't want to have
to urinate gallons and gallons of ammonia every
day. Instead, we convert the ammonia to the
slightly less toxic compound urea.
concentrate urea more than ammonia, so we can
urinate less and conserve water.
birds, on the other hand, convert ammonia to uric
acid, which is even less toxic than urea. In
fact, uric acid doesn't need any water at all --
they can excrete it as a solid and conserve as
much water as possible. If you've ever had the
good fortune to take a good look at bird
droppings, you've probably noticed that they tend
to have black chunks (the feces) in a white pasty
substance. This white stuff is mostly the uric
acid. If you want some bonus vocabulary to impress
your friends, here goes: ammonia-excreting
animals are 'ammonotelic', mammals and anything
else that uses urea are 'ureotelic', and the birds
and reptiles are 'uricotelic.'
Birds crystallize their urine and excrete it,
along with feces, out their cloacas (a hole that
has been turned inside-out in mammals, including
the urinary excretory oriface, the anus, and, in
females, the vaginal opening).
Yes, birds excrete urine. Birds have only one
pathway to excrete any substance called a cloaca,
so all the fluids and materials they excrete pass
through the cloaca, usually in a mixed form.
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