Whales must breathe air. They are classified as marine mammals, meaning they possess lungs and rely on atmospheric oxygen for survival, unlike fish, which use gills. Whales retain the core characteristics of all mammals, including being warm-blooded and giving birth to live young. This biological necessity requires them to periodically rise to the surface to exchange gas.
The Anatomy of Whale Respiration
The whale’s respiratory system is uniquely structured for its aquatic life, starting with the blowhole, which functions as the whale’s nostril. This opening is positioned on top of the head, allowing the animal to breathe without lifting its entire body out of the water.
Beneath the blowhole, an anatomical feature separates the respiratory tract from the digestive tract. Unlike land mammals, the whale’s larynx and trachea connect directly to the blowhole, bypassing the esophagus and mouth. This separation ensures the whale can feed underwater without inhaling water into its lungs. Toothed whales possess a single blowhole, while baleen whales are equipped with two openings.
Specialized Diving Adaptations
The ability of whales to remain submerged for extended periods stems from physiological modifications. One of the most significant is the high concentration of oxygen-storing proteins in their body tissues. Whale muscles are dense with myoglobin, a protein that binds oxygen far more efficiently than the hemoglobin found in the blood. Deep-diving cetaceans can store several times more oxygen in their muscles than terrestrial mammals.
This specialized oxygen storage is coupled with the mammalian diving reflex, a coordinated response that conserves the available oxygen supply. When a whale dives, its heart rate drops (bradycardia). Simultaneously, peripheral vasoconstriction occurs, restricting blood flow to non-essential organs and redirecting oxygenated blood primarily to the heart and brain. Furthermore, the whale’s lungs and airways are built to manage the crushing pressure of the deep ocean. Their highly compressible tracheas and bronchi allow the lungs to collapse safely, forcing residual air into the reinforced upper airways where nitrogen cannot be absorbed into the bloodstream, thus preventing decompression sickness.
The Behavior of Breathing
The act of breathing in whales is an efficient and conscious process, unlike the involuntary breathing of humans. When a whale surfaces, the first action is a powerful, rapid exhalation through the blowhole. This forceful expulsion clears the airway of stale air in a fraction of a second.
The visible plume, or “blow,” that observers see is not water but a cloud of warm, moist air condensing rapidly upon contact with the cooler atmosphere. This exhalation replaces up to 90% of the air in the whale’s lungs with a single breath, a rate far superior to the 10-15% exchange rate of a human. Immediately following the exhalation, the whale takes a deep, rapid inhalation before sealing its blowhole with muscular plugs and resubmerging. The entire respiratory exchange can occur in as little as one to two seconds for some species.