What is a Blowhole and How Does it Work?
A blowhole is a hole on the top of the head of some marine mammals, such as whales, dolphins and porpoises, that allows them to breathe air. It is not a nose, but rather a modified nostril that connects to the respiratory system. When the animal surfaces, it exhales a burst of air and water through the blowhole, creating a spray or spout. Then it inhales fresh air before diving again.
Blowholes are adapted to the aquatic lifestyle of these animals. They can be closed by muscles or valves to prevent water from entering the lungs. They also allow the animal to breathe without lifting its head out of the water, which saves energy and reduces exposure to predators. Some species have one blowhole, while others have two. The number and shape of blowholes can help identify different types of whales and dolphins.
Types of Blowholes
There are two main types of blowholes: single and double. Single blowholes are found in toothed whales (odontocetes), such as sperm whales, killer whales and dolphins. They are located on the left side of the head, slightly behind the eyes. Double blowholes are found in baleen whales (mysticetes), such as humpback whales, blue whales and gray whales. They are located on the top of the head, near the front.
The shape and size of the blowholes vary among species and individuals. Some have round or oval openings, while others have slit-like or crescent-shaped ones. Some have protruding or raised blowholes, while others have flat or sunken ones. The diameter of the blowholes can range from a few centimeters to over a meter.
How Blowholes Work
Blowholes work like valves that open and close to regulate air flow. When the animal dives, the blowholes are closed by muscles or flaps of skin to prevent water from entering. When the animal surfaces, it opens the blowholes and exhales forcefully, creating a spout of air and water that can reach several meters high. The spout is visible from a distance and can help locate whales and dolphins at sea. The shape and direction of the spout can also indicate the species and behavior of the animal.
After exhaling, the animal inhales quickly through the blowholes before diving again. The inhalation takes only a fraction of a second, but it fills up to 90% of the lung capacity. The lungs of marine mammals are specially adapted to withstand high pressure and low oxygen levels underwater. They can store more oxygen in their blood and muscles than land mammals. They can also collapse their lungs partially or completely to avoid gas exchange at depth, which prevents decompression sickness.
The breathing cycle of marine mammals depends on their activity level and diving depth. Some species can hold their breath for over an hour, while others need to surface more frequently. Generally, they breathe more often when they are active or feeding near the surface, and less often when they are resting or diving deep.
Fun Facts About Blowholes
- The sound of a whale’s or dolphin’s breath is called a “chuff”. It can be loud enough to be heard from several kilometers away.
- Some species can use their blowholes to make vocalizations, such as clicks, whistles and songs. These sounds are used for communication, navigation and echolocation.
- Some species can also use their blowholes to spray water or air at other animals or objects, such as boats or birds. This behavior can be playful, aggressive or defensive.
- Some species have special adaptations related to their blowholes. For example, sperm whales have a large cavity called the “spermaceti organ” above their single blowhole, which helps them regulate their buoyancy and produce powerful clicks for echolocation. Narwhals have a single blowhole that is twisted to the left side of their head, which allows them to break through ice with their long tusk.