How do whales breathe?

Quick Answer

Whales breathe by surfacing and inhaling atmospheric air through blowholes, which are modified nostrils located on the top of their heads. Unlike fish, which extract oxygen from water using gills, whales are mammals with lungs that function similarly to our own—but with vastly superior efficiency.

When a whale surfaces, it forcefully exhales stale air (creating the famous “spout” or “blow”), then quickly inhales fresh oxygen before diving again. Strong muscular flaps called nasal plugs seal the blowholes tightly when the whale is underwater to prevent water from entering the lungs.

The efficiency of a whale’s respiratory system is staggering. While humans only exchange about 10% to 15% of the air in our lungs with each breath, whales can exchange up to 90% of their lung volume in a single second. This rapid gas exchange allows massive species like the Blue Whale to oxygenate their blood almost instantly, preparing them for deep dives and long periods without air.

For more details on the physical structure of these marine giants, visit our guide to Anatomy.

---

In-Depth Explanation

To understand how whales breathe, we must look at their evolutionary history, their unique physiology, and the chemical adaptations that allow them to thrive in an environment where they cannot breathe.

The Blowhole: Evolution’s Snorkel

The most distinct feature of whale respiration is the position of the nose. Over millions of years of Evolution, the nostrils of whale ancestors migrated from the tip of the snout to the very top of the skull. This adaptation allows the animal to breathe while keeping the majority of its body submerged, maintaining momentum while swimming.

There is a distinct difference in blowhole structure between the two primary groups of whales:

• Mysticetes (Baleen Whales): Species like the Humpback and Right Whale possess two side-by-side blowholes, similar to human nostrils.
• Odontocetes (Toothed Whales): Species like the Sperm Whale and Killer Whale have only one blowhole.

Surrounding the blowhole are powerful muscles that keep the airway logically “closed” at rest. Unlike humans, whose airways are open by default, a whale must exert muscular effort to open its blowhole. This passive-closing mechanism ensures that if a whale loses consciousness or relaxes completely, water will not flood its lungs.

The “Spout” Phenomenon

A common misconception is that whales spout water out of their heads. If water entered the lungs, the whale would drown. The visible spray, often called the “blow,” is actually a combination of three things:

1. Hot Air: The air inside a whale is body temperature (roughly 98.6°F or 37°C). When this hot air hits the colder sea air, it condenses instantly into mist, much like seeing your breath on a cold winter day.
2. Mucus and Oil: The blowhole contains naturally occurring oils and mucus to lubricate the opening and trap bacteria, which are expelled during exhalation.
3. Surface Water: A small amount of water resting on top of the blowhole is blasted upward when the whale exhales.

Oxygen Storage: The Biochemistry of Diving

While big lungs help, the secret to how whales breathe less often lies in their blood and muscles. Whales have a significantly higher volume of blood relative to their body size than terrestrial mammals.

Their blood is rich in hemoglobin (which carries oxygen in the blood), and their muscles are packed with myoglobin (which stores oxygen in muscle tissue). Myoglobin acts as an onboard oxygen tank, allowing the whale to continue functioning even when its lungs are compressed or empty.

When a deep-diving species like the Cuvier’s beaked whale descends, it actually collapses its lungs to prevent nitrogen bubbles from entering the bloodstream—a condition known as “the bends” in human divers. They rely almost entirely on the oxygen stored chemically in their muscles to survive the dive.

Conscious Breathing

Perhaps the most alien aspect of whale respiration is that it is voluntary. Humans are “involuntary breathers”; if you faint, your brain stem continues to regulate your breathing. Whales are “conscious breathers.” They must actively decide to take every breath.

This physiological requirement dictates their entire lifestyle, particularly how they rest. If a whale were to fall completely unconscious, it would stop breathing and suffocate. This leads to unique sleep behaviors where only half of their brain shuts down at a time. You can read more about this phenomenon in our article on how do whales sleep.

---

Key Comparisons

The respiratory capabilities of whales vary significantly depending on their species and ecological niche. Below is a comparison of breathing adaptations across different marine mammals and humans.

Baleen vs. Toothed Whales

The primary visual difference in breathing mechanics is the blowhole count, but the “blow” shape also differs, helping scientists identify species from a distance.

Feature	Baleen Whales (Mysticetes)	Toothed Whales (Odontocetes)
Blowholes	Two (side-by-side)	One
Blow Shape	Often tall and straight (e.g., Blue Whale) or V-shaped (e.g., Right Whale)	Often angled forward and to the left (e.g., Sperm Whale)
Primary Dive Type	Generally shallower, shorter dives (feeding on krill)	often deep, long dives (hunting squid/fish)
Example Species	Fin Whale, Humpback	Orca, Beluga, Narwhal

Whales vs. Humans

The efficiency gap between human and cetacean respiration is massive.

• Gas Exchange: Whales exchange 80-90% of lung air per breath; humans exchange 10-15%.
• Breathing Rate: A resting human breathes 12-20 times per minute. A large whale may breathe only once every few minutes at the surface, and hold that breath for hours underwater.
• CO2 Tolerance: Whales have a much higher tolerance for carbon dioxide buildup in their blood, which is the primary trigger that makes humans feel the “urge” to breathe.

Gills vs. Lungs

It is crucial to distinguish whales from fish like the Whale Shark.

• Fish (Whale Shark): Use gills to extract dissolved oxygen directly from the water. They do not need to surface to breathe.
• Mammals (Whales): Use lungs to process gaseous oxygen. They must surface. If a whale is trapped underwater by fishing gear, it will drown, just as a human would.

---

Related Questions

How long can whales hold their breath?

Whales are the champions of breath-holding. While surface-feeding species may only dive for 10-20 minutes, deep divers like the Sperm Whale can stay submerged for over an hour. The current record holder is the Cuvier’s beaked whale, which has been recorded diving for nearly 4 hours on a single breath. Read more: How long can whales hold their breath

Can whales breathe through their mouths?

No. Unlike humans, a whale’s trachea (windpipe) and esophagus (food pipe) are completely separated. This is an essential adaptation that allows them to swallow prey underwater without accidentally flooding their lungs. They can only breathe through their blowholes. This anatomical separation also means whales cannot choke on food in the same way humans do.

How do whales sleep without drowning?

Since whales are conscious breathers, they cannot enter a state of full unconsciousness like humans do. Instead, they engage in unihemispheric slow-wave sleep. This means they shut down one half of their brain to rest while the other half remains alert to ensure they stay near the surface and continue breathing. Read more: How do whales sleep

Can a whale drown?

Yes. Because they breathe air, whales can drown if they are unable to reach the surface. This most commonly happens when whales become entangled in fishing nets or heavy lines that weigh them down, preventing them from surfacing to breathe. It can also occur if a newborn calf is too weak to swim to the surface immediately after birth (though the mother usually assists).