"Because desert tortoise live in an arid climate where most of the rainfall occurs during the monsoons, it is able to store water in its bladder for use during drought. It can go over a year without drinking. One of its defense mechanisms when handled or disturbed is to release the contents of its bladder, which can deplete its water supply and can cause harm or death during a drought. For this reason, if you find a desert tortoise, do not pick it up."Interesting that it can harvest water from the bladder. Mammalian bladders have a transitional epithelium that is virtually impermeable to water. But I found an NCBI article that documents reabsorption of water from Gila monster bladders, so presumably the same adaptation has evolved in tortoises.
With a hat tip to the QI elves...
At least some crocodiles also do this (but not alligators). It's a method to counteract the dehydrating effect of living in saltwater. Their urine can actually be solid if they've recently spent a lot of time in a highly saline environment.
ReplyDeleteI lived in the deserts of Namibia for two years, which involved lots of walking. It was a noticeable trend there to not carry water when walking. Instead they would drink a large quantity just before departing and I adopted the same habit by the end of my time there. It certainly FELT like one reabsorbed water from the bladder using that method.
ReplyDelete