Turtles Can Breathe Through Their Butts
Some species of turtles — notably the Australian Fitzroy River turtle and the North American eastern painted turtle — can breathe air through their butts. They can of course breathe normally through their mouths too, which really makes us wonder: why breathe through your butt if you can breathe through your mouth? The answer is that they generally only use this ability while hibernating for long periods of time during winter (sometimes up to 5 months) or when they take a nap underwater.
Turtles have a rear opening called a cloaca which they use for pooping, peeing, mating and laying eggs. And in addition to that, the butt-breathing species have special sacs in their cloaca called bursae, which absorb oxygen from the water across blood vessels. This is different to breathing in air through a snorkel or nose and is more about oxygen absorption. As a result, these turtles expend less energy breathing while they hibernate or nap underwater.