How Do Whales Breathe? Blowholes, Spouts and Lungs

What is a blowhole?

A blowhole is a whale’s nostril. Over millions of years of evolution, the nostrils of whale ancestors moved from the tip of the snout to the top of the head, so a whale can breathe with only a small part of its body above water. Whales are mammals, not fish, as explained in Are whales fish?, and they have no gills.

Baleen whales, such as the humpback whale, have two blowholes set side by side in a shallow V, surrounded by a raised ridge that helps keep water out. Toothed whales, including dolphins and orcas, have a single blowhole. The sperm whale’s is unusual: it sits on the front left of its huge head and is actually the left nostril only.

Each blowhole is closed by muscular plugs. When the whale is relaxed, the plugs stay shut, so the blowhole is sealed underwater without any effort. To breathe, the whale contracts muscles that pull the plugs open.

Can whales breathe through their mouths?

No. In whales the windpipe connects only to the blowhole, completely separate from the mouth and throat. This means a whale can open its mouth underwater to gulp food without any risk of water getting into its lungs.

Toothed whales also use their nasal passages to make sounds. Air pushed through structures just below the blowhole produces the clicks dolphins use for echolocation, all without opening the blowhole. Humpbacks can release air from their mouths too, which they use when making bubble nets.

What is a whale’s spout made of?

The spout, or blow, is not a fountain of water from the lungs. It is the whale’s breath. Warm, moist air from the lungs is pushed out at high speed, and as it expands and cools, the water vapor condenses into a cloud of tiny droplets, much like your breath on a cold day. Seawater sitting around the blowhole is blasted upward too, and so are droplets of mucus.

Scientists now collect this “whale snot” with drones flying through the blow. Samples can reveal a whale’s DNA, stress and pregnancy hormones and the microbes in its airways, without touching the animal.

Identifying whales by their spout

Because blowholes differ in size, shape and position, many whales can be identified from a distance by their blow. Height varies with the whale’s size, the wind and the force of the breath, so the figures below are rough guides.

How long can whales hold their breath?

Most whales dive for a few minutes to about 20 minutes, but deep divers stay down much longer. Humpbacks usually dive for less than about 15–20 minutes. Feeding blue whales off California average about 10 minutes per dive. Sperm whales commonly dive for 45 minutes to an hour. The record belongs to Cuvier’s beaked whale: one tagged off North Carolina stayed underwater for 222 minutes, more than three and a half hours. More on record divers is in How deep can whales dive?

Whales manage long dives by storing oxygen in their blood and muscles rather than relying on air in their lungs. Their muscles are packed with myoglobin, an oxygen-holding protein, and their heart rate slows sharply during a dive. A study of a tagged blue whale recorded a heart rate as low as 2 beats per minute at depth, rising to about 37 beats per minute when it surfaced to breathe. Deep-diving whales also let their lungs partly collapse under pressure, which keeps nitrogen out of the blood and reduces the risk of decompression sickness.

How fast do whales breathe?

Whale breaths are fast and deep. The explosive exhalation and the inhalation that follows take only a few seconds, even in the largest whales. Each breath replaces most of the air in the lungs, often quoted as around 80–90%, compared with roughly 10–15% for a resting person. A humpback’s lungs have been estimated to hold about 5,000 liters (1,300 gallons) of air.

Before a long dive, whales usually take a series of breaths at the surface to load up on oxygen, and after a deep dive they breathe repeatedly to recover. Watching this breathing rhythm is how whale watchers predict when a whale is about to dive, often lifting its tail as it goes down.

Do whales breathe while they sleep?

Whales are conscious breathers: each breath is a deliberate act, not an automatic reflex as in humans. That creates a problem when they sleep. Dolphins solve it by resting one half of the brain at a time while the other half keeps watch and controls breathing, as described in How do dolphins sleep?

Sperm whales have been seen taking short naps while hanging motionless and vertical just below the surface, then rising to breathe. How the largest baleen whales sleep is still poorly understood, because they are difficult to watch for long periods.