How can a whale stay under water for so long?
These deep-diving mammals have numerous adaptations that enable them to extend their breath-holding time and to avoid the diving maladies (the bends and nitrogen narcosis) that plague human divers. The important factor in avoiding the effects of pressure is that the lungs of deep-diving mammals are able to collapse completely. All the air is then compressed into the large air ducts and nasal passages, where no additional gas exchange takes place with the blood. This explains how they avoid the bends and narcosis—no excess gas enters the blood during the dive.
