8. Respiratory System Modifications
Sloths have developed special adaptations for their energy-conservative way of existence that fit their respiratory system. With reinforced diaphragm muscles that can operate in any posture, their lungs have evolved specialised features that enable them to breathe adequately even when hanging upside down. < With extra branches improving oxygen extraction efficiency, the bronchial tree has developed to be more sophisticated than in other mammals. Though their breathing rate is quite slow—sometimes as low as one-third the rate of similarly-sized mammals—their highly effective gas exchange systems help to maintain appropriate oxygen levels. The specialised elastic qualities of the blood arteries in their lungs have helped to stop fluid collection under inverted posture. This respiratory adaptation shows how evolution has changed fundamental mammalian organ systems to produce extremely specialised answers for certain living needs.