Answer: Limited room and no ribcage
Pls give me brainliest i had to research
Explanation: The possible answer to the question lies in the turtle's shell. The shell, which evolved from ribs and vertebrae that flattened out and fused together, does more than keep the turtle safe from bites. When a turtle hibernates, it buries itself in cold water for up to five months. To survive, it has to change a lot of things about the way its body works. Some processes, such as fat burning, go anaerobic - or without oxygen - in a hibernating turtle. Anaerobic processes result in the build up of lactic acid, and anyone who has seen Aliens knows that too much acid isn't good for a body. The turtle's shell can not only store some lactic acid, but release bicarbonates (baking soda to the acid's vinegar) into the turtle's body. It's not just armor plating, it's a chemistry set.
It is, however, a fairly restrictive chemistry set. Without ribs that expand and contract, the turtle has no use for the lung and muscle set-up that most mammals have. Instead it has muscles that pull the body outwards, towards the openings of the shell, to allow it to inhale, and more muscles to squish the turtle's guts against its lungs to make it exhale. The combination makes for a lot of work, which is especially costly if every time you use a muscle your body's acid levels go up and oxygen levels go down.
Compare this to the relatively cheap butt breathing. Sacs next to the cloaca, called bursa, easily expand. The walls of these sacs are lined with blood vessels. Oxygen diffuses through the blood vessels, and the sacs are squeezed out. The entire procedure uses little energy for a turtle that doesn't have a lot to spare. Dignity has to play second-fiddle to survival sometimes.
