Final answer:
Rabbits are obligate breathers through their nares, meaning they breathe only through their noses. Nasal breathing is more efficient for filtering and moistening the air. Rabbits do not have a flow-through respiratory system like birds but instead have a typical mammalian respiratory system with alveolar sacs.
Step-by-step explanation:
The term 'obligate breather' refers to organisms that breathe exclusively through one respiratory pathway. For rabbits, this means they are nares breathers; they breathe only through their noses. Rabbits are designed this way because nasal breathing filters particles, warms, and moistens the air more efficiently than mouth breathing, which is beneficial for their overall respiratory health. The structure of the mammalian respiratory system includes the alveolar sac, which is a crucial part of the lung where gas exchange occurs with the blood. While some animals have a flow-through respiratory system, such as birds, that allows air to move in a unidirectional flow, rabbits do not possess this type of system.