The whale blowhole is an essential anatomical feature for marine mammals, allowing them to breathe air efficiently at the ocean’s surface. This specialized opening on top of their heads is a testament to their evolutionary journey from land-dwelling ancestors to fully aquatic life.
Measuring the Blowhole’s Size
The size of a whale’s blowhole varies considerably across species, depending on whether the whale is a baleen whale or a toothed whale. Baleen whales, such as blue whales and humpbacks, possess two blowholes, typically positioned side-by-side and appearing as a single, large opening. A blue whale’s blowhole can measure up to 20 inches (50 centimeters) in length. Gray whale blowholes are also substantial, reaching about 8 inches (20 centimeters) long.
Toothed whales, including sperm whales, dolphins, and porpoises, have only one blowhole. The sperm whale, the largest toothed whale, features a single, S-shaped blowhole about 20 inches (50 centimeters) long, distinctly located on the left side of its head. Smaller toothed whales, like bottlenose dolphins, have blowholes typically around 6 centimeters in diameter. These size differences relate to the whale’s overall body size and its respiratory needs.
How Blowholes Function
The blowhole’s primary function is respiration, enabling whales to breathe air efficiently at the water’s surface. Its dorsal placement means whales do not need to lift their entire head out of the water to inhale. Unlike land mammals, whales cannot breathe through their mouths, as their respiratory and digestive systems are not connected. The blowhole serves as the sole pathway for air to enter and exit their lungs.
When a whale surfaces, it forcefully expels air through the blowhole, creating the visible “blow” or “spout.” This consists of warm, exhaled air, water vapor, and sometimes mucus or oils, not water from their lungs. The water vapor condenses into a misty cloud upon contact with the colder atmosphere, much like human breath on a cold day. The unique shape and height of the blow can help researchers identify different whale species from a distance.
Beyond breathing, the blowhole plays a role in sound production for some species. Toothed whales utilize air sacs located just below the blowhole to generate sounds for communication and echolocation. These sounds are crucial for navigating their underwater environment and locating prey.
Anatomy and Mechanism
The blowhole is a modified nostril that has migrated to the top of the whale’s head over evolutionary time. This repositioning provides a significant advantage, allowing whales to breathe quickly and easily while remaining mostly submerged. The structure involves complex musculature and cartilaginous components that facilitate its precise control.
Strong muscles surrounding the blowhole actively contract to open it when the whale surfaces to breathe. When a whale dives underwater, these muscles relax, allowing fibrous plugs or nasal plugs to seal the blowhole tightly. This sealing mechanism is important for preventing water from entering the respiratory system and lungs. Whales exhibit voluntary control over their breathing, consciously opening and closing the blowhole. This rapid and efficient breathing cycle allows whales to exchange 80 to 90 percent of the air in their lungs with each breath, a much higher rate compared to the 10 to 15 percent exchanged by humans.