It is true that sharks do not have bladders like most fish. Some species depend entirely on their forward motion to keep fresh water moving over their gills. These species can stop moving for short periods of time (like you holding your breath for a few minutes), but the longest they can last is a few hours. That's where the myth came from that all sharks must constantly move.
So if a shark falls into the Mariana Trench and develops lungs, is it still really a shark?
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branchandroot
Miss Biology at your Service
Date: 2003-04-27 09:10 am (UTC)So if a shark falls into the Mariana Trench and develops lungs, is it still really a shark?
Have fun.
Coyote.