Views: 1599 | Comments: 2
Last by Cynthia McKelvey on Apr 09, 2012, 12:46pm
Why yes, penguins do have an organ that converts sea water into fresh water! Except it's not an organ, it's a gland. And it doesn't directly convert sea water to fresh water, it filters salt from the blood.
Hm, maybe I should start from the beginning.
First of all, this organ/gland/whatever that Dean is talking about is called the supraorbital gland, and it's something all marine birds have. Basically any mammal or bird that is going to have to drink sea water to quench thirst is going to need this gland.
Normally, salt that we ingest is absorbed into the blood stream, filtered out by the kidneys, and secreted in urine. However, the penguin's small kidneys can only filter out enough salt to create urine that's about 1/3 the concentration of sea water. If the blood is still too salty, then water must be taken from other tissues to dilute it, and this quickly leads to dehydration.
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