|MadSci Network: Zoology|
Dear Michael, Marine fish use their hyper-osmotic blood to draw in water, while freshwater fish have to maintain the hypo-osmotic condition to avoid flooding. The swim bladder is never involved as far as I know.Your search for an actual organ containing water could include the Australian desert frog, which uses its whole body to absorb water within two minutes, when in its dessicated, dry-season condition. Aborigines use them for drinking water. In this context, I imagine the Anuran bladder could be regarded as your water container. Frogs use it for resorption, just as you (and other mammals) resorb in a discriminating fashion from the colon. The size of insects probably restricts their capacity to retain much water, but they have similar absorptive abilities to the frogs. The mealworm, Tenebrio molitor is your best example.
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