How do whales and dolphins breathe?

Unlike fish, which extract oxygen from water using gills, whales and dolphins are marine mammals that breathe atmospheric oxygen through their lungs. They have a special opening on top of their heads called a blowhole, which functions like a nose. This allows them to inhale air and exhale carbon dioxide. During dives, the blowhole remains tightly closed by powerful muscles to prevent water from entering the respiratory system. When whales surface, they open the blowhole and release a strong burst of air and vapor before taking a deep breath and diving again. You’ve probably seen this famous fountain-like spout in photos before.

How long can they stay underwater?

Dolphins can typically hold their breath for 8–15 minutes, while large whales can stay submerged for up to 60 minutes. The record-holder, however, is the Cuvier’s beaked whale, which can dive for more than two hours and fifteen minutes in a single breath! This ability comes from their high concentrations of hemoglobin and myoglobin — two proteins that store oxygen in the blood and muscles — and their ability to slow their heart rate during deep dives to conserve oxygen.

If they breathe air, why do they die on land?

Whales and dolphins do not die immediately from suffocation when they are out of the water, because they breathe air through their blowholes, and technically, they can still inhale and exhale in open air. However, they do eventually die if they remain beached, but not primarily because they can’t breathe. The real causes include:

1. Crushing weight and internal pressure is deadly for whales and dolphins

A blue whale can weigh over 150 tons (150,000 kilograms). While in water, buoyancy supports its massive body weight. But once ashore, gravity exerts full pressure on its organs — especially the lungs and heart — causing them to collapse or stop functioning. Their skeletons are not designed to support such weight outside the water, leading to fatal internal injuries.

2. Overheating and thermal stress

Whales and dolphins have a thick layer of fat called blubber, which can be up to 30 centimeters thick and serves as insulation against cold ocean waters. However, this same insulation becomes dangerous on land, where there’s no water to cool their bodies. Their internal temperature rises rapidly, leading to thermal stress, tissue damage, and dehydration.

3. Dehydration and skin damage

Their skin is adapted to stay constantly moist. Once exposed to air, it begins to dry, crack, and lose moisture rapidly. This is why rescuers are often seen spraying water or covering whales with wet cloths — to keep them hydrated until they can return to the ocean.

4. Limited mobility and physical exhaustion

Whales and dolphins have streamlined bodies designed for efficient movement in water. On land, this adaptation becomes a hindrance; they cannot move or support themselves, causing muscle fatigue, compression injuries, and eventually death from exhaustion.

5. Starvation and energy depletion

These giants have enormous energy demands. A blue whale, for instance, consumes around 40 million krill per day — roughly 2–10% of its body weight. When stranded, they lose access to food and quickly run out of energy, leading to starvation.

Why do whales beach themselves in the first place?

Whale and dolphin strandings have been documented for centuries — with around 2,000 incidents recorded worldwide each year. Yet, the exact cause remains one of the great mysteries of marine biology. Some of the main theories include:

1. Illness or old age: Sick or elderly whales may deliberately isolate themselves and drift toward shore to die peacefully.

2. Geological disturbances: Underwater earthquakes or volcanic activity can disrupt their navigation systems.

3. Human interference and sonar noise: Naval sonar systems emit powerful sound waves that can disorient whales, causing them to flee in the wrong direction — often toward shallow waters. A famous example occurred in 2000 in the Bahamas, when 17 whales beached shortly after a U.S. Navy sonar test.

 What should be done when a whale is stranded?

When rescuers discover a stranded whale or dolphin, every second counts. They immediately begin keeping the animal’s skin moist, using buckets of seawater or wet cloths. Wet towels or blankets are gently placed over its body to prevent the skin from overheating or drying out. Next, rescuers adjust the animal’s position, easing the weight off its chest and fins to help it breathe more easily. Throughout the process, they have to stay calm and quiet — sudden noises can cause panic. Meanwhile, marine rescue authorities should be contacted to organize professional equipment and a safe return to the sea.

Now is clearer why whales and dolphins can’t live outside of water

Although whales and dolphins are air-breathing mammals, their bodies are precisely engineered for life in the ocean. Once on land, they face a deadly chain of effects — from internal pressure and overheating to dehydration and organ failure — that ultimately leads to their death within hours. Understanding this phenomenon is crucial not only for science but also for improving marine rescue and conservation efforts.

Respiration as a vital process

Oxygen keeps life alive. It fuels every cell, giving living things the power to move, grow, and stay alive. Humans get oxygen through their lungs, pulling it from the air with each breath. The lungs send it into the blood, which carries it to every part of the body. In return, carbon dioxide leaves as waste. But for creatures under the sea, things work differently. There’s no air to breathe, only water. Over millions of years, marine life developed amazing ways to take in the oxygen hidden within it.

How do fish breathe underwater?

Fish don’t have lungs like we do. Instead, they breathe through special organs called gills. These gills handle the vital job of swapping gases — taking in oxygen and letting out carbon dioxide. Each gill is made of thin, delicate filaments filled with tiny blood vessels. That’s what gives them their bright red color. Most fish have four pairs of gills, but some, like sharks, can have as many as seven. When a fish opens its mouth, water flows in and washes over the gills. The blood inside the filaments collects the oxygen dissolved in the water and releases carbon dioxide in return. Then, the used water slips out through the gill openings — just like water draining through a strainer.

The challenges of breathing underwater

Although fish appear well adapted, underwater respiration is actually a demanding process. Water contains only about 8 milligrams of oxygen per liter, while air contains nearly 210 milligrams per liter — over 25 times more. Furthermore, oxygen levels drop significantly in deeper waters, meaning fish must rely on highly efficient oxygen-extraction systems to survive in such conditions.

Dual breathing in certain species

Not all fish depend solely on gills. More than 450 fish species can breathe air directly using dual respiratory systems, which combine gills, lungs, or even skin surfaces.

Examples include:

• The Mudskipper: Native to Southeast Asia, it can live up to six consecutive days outside the water, breathing directly through the air.
• The Catfish: Known in Egypt as Qarmout, this fish can survive on land as long as its skin remains moist.

Marine mammals — a unique case

Whales and dolphins are not fish, but marine mammals that breathe air through lungs. They have a special opening on top of the head called a blowhole, which closes tightly while diving and opens when they reach the surface to inhale air. Whales can store large amounts of oxygen in their bodies, allowing them to stay submerged for up to 60 minutes, while dolphins can usually hold their breath for 8–10 minutes.

Now you understand how marine life breathe underwater

Respiration in marine life is one of the most remarkable examples of biological adaptation. While fish use gills to extract oxygen from water, marine mammals rely on lungs to breathe air, illustrating the extraordinary diversity and intelligence of life beneath the waves. Understanding these mechanisms deepens our appreciation of marine biology and contributes to global conservation efforts aimed at protecting the delicate balance of ocean ecosystems. If you’re inspired to explore this hidden world yourself, Hurghada Today offers unforgettable sea trips where you can witness the beauty of marine life up close.