exhaling through the mouth, using the phrase, "the nose is for breathing, the mouth is for eating." Elsewhere in the animal kingdom Lambs are noted to only switch to mouth breathing when the nasal passages are completely obstructed, with hypoxaemia having developed also as a result. References Further reading External links Effects of Mouth Breathing - WebMD (video clip) Biological anthropology Breathing abnormalities Dentistry Mouth Orthodontics Symptoms and signs: Respiratory system