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Re: could / did sauropods drink?
>I'm fuzzy on this but they manufacture their own water from their food
>metabolically (Can anybody fill us in on this?). Though the usual "apples
>and oranges" (or in this case "sauropods and kangaroo rats") caveats apply,
>we apparently can't rule out the possibility that sauropods, too, were
>Jeffrey Willson <email@example.com>
In response to the metabolic water question, here's an extract from my
forthcoming book *Why elephants hae big ears* - available at all good
bookshops from May, a snip at only £17.99 etc.
"The only moisture available to an oryx in the absence of drinking-water is
from the food it eats. All plants contain some free water and this can
simply be extracted as the material is mashed in the mouth and stomach. The
vegetation favoured by oryx often contains as little as 1% water by weight
during the day, but this can increase twenty-fold at night as the
temperature falls, humidity rises and desert plants scavenge water directly
from the air. So by eating at night, oryx exploit the survival tactics of
their food-plants to rehydrate themselves.
Water is also one of the main bi-products of metabolic reactions -
carbohydrate and oxygen react together to give carbon dioxide and water -
so all animals have an indirect way of getting moisture from their food.
However, while metabolic reactions produce water they also require oxygen,
and water is lost from an animal's lungs every time it exhales. Under
normal circumstances, the loss of water associated with respiration equals
or exceeds the gain from metabolic processes, so an increased rate of
metabolism is unlikely to help an animal balance its water budget. The
amazing oryx, however, has even found a way of squeezing excess water out
of its metabolic reactions. At night when they are radiating stored heat
back into the environment and while the air is relatively humid, oryx begin
to inhale and exhale very slowly and very deeply. Deep breaths allow more
oxygen to be extracted from each lung-full of air and more metabolic water
to be manufactured without increasing the number of breaths. Provided the
relative humidity of the air stays above 70% for most of the night, a
deep-breathing oryx will end up with more water inside its body at dawn
than it had the previous evening. The production of concentrated urine,
daytime heat-storage, and nocturnal eating, heat-dumping and deep-breathing
allow oryx to pull off the amazing feat of surviving the hottest desert
environments without having to drink."