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How do whales breathe?

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Quick answer

Whales breathe air through blowholes on top of their heads. At the surface, muscles open the blowhole, the whale exhales forcefully and inhales quickly, then seals it shut and dives. Oxygen stored in blood and muscle, a slowed heart and blood redirected to the brain and heart let some species stay underwater for an hour or more.

Whales breathe air through blowholes on top of their heads, surfacing to exhale and inhale in a quick burst before diving again. They store oxygen in blood and muscle, slow their heart and limit blood flow to non-essential organs, which lets some species stay underwater for an hour or longer.

Step by step

  1. The whale rises to the surface, bringing its blowhole into the air first.
  2. Muscles open the blowhole and the whale exhales forcefully, producing a visible spout of condensed breath.
  3. It inhales rapidly, refilling its lungs, and oxygen loads into blood haemoglobin and muscle myoglobin.
  4. The blowhole snaps shut and the whale dives, slowing its heart and limiting blood flow to non-essential organs.
  5. As stored oxygen runs low, the whale returns to the surface and repeats the breathing cycle.

Key things to understand

  1. Whales are mammals with lungs, so they must reach the surface to breathe air rather than extracting oxygen from water.
  2. Their nostrils evolved into blowholes on top of the head, letting them breathe with only a small part of the body exposed.
  3. Baleen whales have two blowholes, while toothed whales such as dolphins and sperm whales have a single one.
  4. A whale exhales explosively and inhales quickly, replacing most of the air in its lungs with each breath.
  5. Oxygen-binding myoglobin in muscles, a slowed heartbeat and redirected blood flow stretch that oxygen supply during long dives.

Labelled diagram

  1. Blowhole

    Nostrils on top of the head, sealed by muscle flaps underwater.

  2. Spout

    Exhaled warm breath condensing into a visible cloud above the water.

  3. Lungs

    Refill rapidly and collapse safely at depth on long dives.

  4. Oxygen stores

    Myoglobin in muscle and haemoglobin in blood hold oxygen for the dive.

How a whale breathes at the surface

Real-world examples

  • India's Ganges river dolphin, a toothed cetacean related to whales, surfaces every minute or two to breathe.
  • Humpback whales off Hawaii surface several times between dives, each blow visible from boats.
  • Sperm whales dive more than 1,000 metres to hunt squid, staying under for around an hour.
  • Cuvier's beaked whales have been recorded diving close to 3,000 metres, the deepest known for any mammal.

Common mistake

✗ Myth: Whales spout water out of their blowholes.

✓ Fact: The spout is exhaled breath, not water from the body. Warm, humid air from the lungs condenses as it cools, carrying along some mucus and seawater from around the blowhole.

People also ask

How long can whales hold their breath?
It varies widely by species. Many dolphins stay under for a few minutes, while humpback whales usually dive for under 20 minutes. Sperm whales routinely hold their breath for about an hour. Cuvier's beaked whales hold the record, with one dive measured at over two hours.
Do whales breathe air or water?
Whales breathe air. They are mammals with lungs, not gills, so they cannot take oxygen from water and must surface regularly. Their blowholes let them breathe with most of the body still submerged. A whale trapped underwater, such as in fishing nets, can drown.
Why do whales have blowholes?
Blowholes evolved as whales adapted to life in water. Over millions of years their nostrils moved from the tip of the snout to the top of the head. This lets a whale breathe as soon as it breaks the surface, without lifting its head, which saves energy and time between dives.
What is the spout a whale blows?
The spout is warm, moist air from the lungs condensing as it expands and cools, mixed with mucus and seawater sitting around the blowhole. It is not water from inside the whale's body.
How do whales sleep without drowning?
Whales breathe consciously, not automatically. Dolphins and some other toothed whales rest one half of the brain at a time, while sperm whales take short naps hanging vertically near the surface.
Why don't whales get the bends?
Their flexible ribcage lets the lungs compress at depth, pushing air into stiff airways where little nitrogen dissolves into the blood. This reduces, though may not completely eliminate, the risk of decompression problems.
Can whales breathe through their mouths?
No. In whales the windpipe connects to the blowhole and is separated from the throat, so they cannot breathe through their mouths. This lets them feed underwater without water entering the lungs.

Part of the guide: Nature & Earth: Living Things and Rocks →