The blue whale, the largest animal known to have ever lived on Earth, possesses anatomical features enabling its aquatic existence. Its blowhole, positioned on the top of its head, serves as its primary breathing apparatus. This specialized opening allows the whale to breathe air efficiently, a fundamental requirement for all mammals.
Measuring the Blue Whale’s Blowhole
The blue whale’s blowhole is a pair of nostrils that have migrated to the top of the head. These V-shaped openings measure between 40 and 50 centimeters (approximately 20 inches) in length. This size is proportionate to the whale’s massive body, allowing for rapid air exchange.
Powerful muscles surround these nostrils. These muscles are connected to fibrous plugs that seal the blowhole when relaxed, preventing water from entering the respiratory system during dives. The blowhole’s placement on the dorsal surface of the head minimizes the effort required for the whale to surface and breathe.
The Mechanics of Whale Respiration
Breathing for a blue whale is a conscious action, unlike the automatic respiration in land mammals. When the whale surfaces, it contracts the muscles around its blowhole to open it. Respiration begins with a forceful exhalation of stale air, which can reach speeds of over 300 to 370 miles per hour.
This explosive expulsion, known as the “blow” or “spout,” is often visible from a distance. The hot, compressed air from the whale’s lungs condenses upon contact with the colder outside air, creating a cloud of water vapor. While primarily air, the spout can also contain water and oil droplets from the upper respiratory tracts. After this exhalation, the whale inhales fresh air before submerging.
Breathing Strategies of the Blue Whale
Blue whales exhibit specific breathing patterns adapted to their aquatic lifestyle and oxygen demands. When diving deeply to feed, they surface to breathe every 10 to 20 minutes. During lunge feeding closer to the surface, their breathing becomes more frequent, occurring approximately every 5 minutes.
They can hold their breath for extended periods, with some dives lasting up to 90 minutes, though typical dives range from 5 to 20 minutes. Their respiratory system is highly efficient, exchanging about 90% of the air in their lungs with each breath, compared to 10 to 15% for humans. This efficiency is supported by a large lung capacity, holding approximately 5,000 liters of air. Adaptations like a flexible rib cage, reduced blood flow to non-essential organs, and a slowed heart rate enhance their ability to conserve oxygen during prolonged underwater excursions.