If you’ve ever wondered how whales can hold their breath for so long underwater, you’re not alone. Whales are marine mammals, not fish, so they don’t have gills to extract oxygen from the water like fish do.

But they have evolved some amazing physiological adaptations that allow them to dive and swim for extended periods without breathing air.

Here’s a quick answer: No, whales do not have gills. Whales are mammals, so they breathe air into lungs like humans do. But they can hold their breath for a very long time due to specialized adaptations like high myoglobin levels in their muscles, collapsible lungs, and slowed heart rate while diving.

Whales as Mammals, Not Fish

Whales are warm-blooded mammals

Unlike cold-blooded fish, whales are warm-blooded mammals. This means they maintain a constant internal body temperature regardless of the temperature of the surrounding water. The normal body temperature for a whale ranges from 36°C to 37°C (97°F to 99°F).

Whales have a thick layer of insulating blubber beneath their skin that helps retain body heat. The blubber can be up to 50 centimeters thick in some species. Without this fatty insulation, whales would lose too much heat to the frigid waters they inhabit.

Whales breathe through lungs, not gills

Whales do not have gills and cannot filter oxygen from water like fish. Instead, they breathe air into lungs through their blowholes. When a whale surfaces, it exhales stale air and inhales fresh air into its two lung sacs, which are inside its chest cavity.

The exhaled “spout” forms a vapor cloud due to the warm respiratory air mixing with the cooler outside air above the ocean’s surface. This visible spout makes it easy for whale watchers to spot different species of whales.

Whales give live birth and nurse young

Another defining mammalian feature is that female whales give birth to live young rather than laying eggs like fish. Gestation periods range from 9 to 17 months depending on the species. Whale calves are born tail first underwater to minimize drowning risk.

Newborn whales drink milk from their mothers’ mammary glands. Nursing lasts anywhere from 5 months for some smaller toothed whales to 2 years for larger baleen whales. This mother-calf bonding time helps the newborns grow big and strong.

In contrast, shark and fish offspring hatch from eggs and are immediately independent. They do not receive any post-birth care or nourishment from parents.

Here is a comparison of some key traits between whales and fish:

Trait Whales Fish
Body temperature Warm-blooded (36°C-37°C) Cold-blooded
Respiration Lungs & blowhole Gills
Reproduction Live birth & nurse young Lay eggs

While whales may seem like gigantic fish as they swim in the ocean, they are actually more closely related to land mammals than fish on an evolutionary level. From their warm-blooded metabolism to nursing babies with milk, whales exhibit the defining features of being mammals despite their aquatic lifestyle.

Adaptations for Extended Breath-Holding

High myoglobin levels in muscles

Whales have evolved incredibly high levels of myoglobin in their muscles, which acts as an oxygen storage molecule. The myoglobin allows whales to hold oxygen in their muscles when diving underwater for long periods.

For example, sperm whales have myoglobin concentrations 10 times higher than terrestrial mammals! This gives sperm whales enough oxygen storage to stay submerged for over an hour while hunting prey at great depths.

Collapsible lungs

A whale’s lungs are specially adapted to collapse under pressure as the animal dives deeper. This reduces gas exchange and oxygen use during the dive, allowing whales to conserve oxygen. The accordion-like lungs work similarly to a SCUBA diver’s BCD (buoyancy control device), except the whale’s lungs deflate automatically when under pressure at depth.

Pretty cool!

Slowed heartbeat and reduced blood circulation

A resting whale has a heartbeat of about 30-40 beats per minute, while a comparable land mammal (like a cow) has a resting heart rate of 60-100 bpm. When diving, a whale’s heartbeat slows drastically, sometimes as low as just 2-10 beats per minute!

This helps conserve oxygen by reducing blood circulation during the dive. Blood flow is directed only to the brain, heart and lungs, while flow to other organs is restricted.

Efficient oxygen use

Whales also have adaptations that allow them to use oxygen more efficiently. They have a higher concentration of red blood cells and hemoglobin than terrestrial mammals. Their muscles also have a higher percentage of oxidative muscle fibers, which are more efficient at using oxygen to generate energy.

This helps whales make the most out of each breath, maximizing their time underwater.

Behaviors for Longer Dives

Coordinated diving in pods

Whales, such as humpback and sperm whales, often dive in coordinated groups called pods. This helps them forage more efficiently and avoid predators during longer dives. By synchronizing their diving patterns, pods of whales can herd and corral schools of fish or krill into bait balls for easier feeding.

The coordinated movements also allow the whales to take turns surfacing for air while others below continue hunting. This cooperative strategy enables pod members to maximize their time under water on deep dives.

Deep dives followed by surface recovery

Whales routinely make very deep dives, sometimes reaching depths over 1,000 feet, followed by extended surface intervals for recovery. For example, sperm whales may dive for over 45 minutes and reach depths of 3,000 feet to hunt giant squid, their favorite prey.

After these marathon dives into the inky abyss, sperm whales will spend 10-20 minutes floating motionlessly at the surface to rest and oxygenate their blood before submerging again. During recovery, they may engage in slow tail slapping or bobbing movements to aid ventilation.

Unihemispheric sleep allows some breathing

Whales have the remarkable ability to sleep with one half of their brain at a time, known as unihemispheric sleep. This allows the awake brain hemisphere to maintain just enough consciousness for the whale to surface and breathe without fully awakening.

Groups of whales sleeping at the surface will synchronize their breathing patterns. A pod of four whales may all surface together for a quick breath before descending back down in unison while half-asleep.

This unihemispheric slumber enables whales to get much needed rest after deep dives while continuing to avoid drowning.

Unique Respiration in Some Whale Species

Sperm whales – 45-60 min dives

Sperm whales are able to hold their breath for an astounding 45-60 minutes while diving to hunt giant squid at depths of over 1,000 meters. They have specially adapted physiology that allows them to store more oxygen and avoid the bends.

Their hemoglobin binds oxygen very tightly, and muscle tissue is rich in myoglobin which also stores oxygen. Before a long dive, sperm whales hyperventilate rapidly at the surface to load up their blood and muscles with oxygen (1).

Sperm whales also have collapsible rib cages that can collapse at high pressure, helping to reduce nitrogen buildup that causes the bends. They also have a slower metabolism during dives to conserve oxygen (2). Their dive durations are the longest of any marine mammal.

Beaked whales – 2+ hour dives

Beaked whales, a family including Cuvier’s beaked whales and Baird’s beaked whales, are champions at long, deep dives. They can hold their breath for over 2 hours and dive deeper than 3,000 feet to hunt and feed (3).

Beaked whales have especially high myoglobin concentrations in their muscles, up to 10 times higher than most other mammals. This allows their muscles to store more oxygen. They also have large spleens and livers to store extra red blood cells and hemoglobin for oxygen storage (4).

Their ribcages are also flexible to withstand pressure at depth. Before dives, beaked whales are able to limit blood flow to some organs and tissues to conserve oxygen for the brain and heart (5). Their diving abilities allow them to live and feed at extreme depths.

Humpback whale ‘bubble nets’

Humpback whales are known for their bubble net feeding technique. A group of humpbacks dive together and exhale air in a spiral motion while swimming upwards. This creates a cylinder of bubbles around their prey like herring or krill.

As the cylinder rises, the prey become confined, allowing the whales to more easily lunge and engulf their food (6).

Researchers have found that humpbacks only use this technique when prey is dense enough for the effort to pay off. The bubbles act as a physical and acoustic barrier that prevents prey from escaping. Bubble net feeding demonstrates advanced intelligence and cooperation among humpback whales (7).

This technique allows them to maximize feeding efficiency while conserving energy during their migration. The ‘bubble nets’ are an example of how whales intelligently adapt their respiration for survival.

Conclusion

While whales don’t have gills to breathe underwater like fish, their bodies are incredibly adapted for long dives through specialized lungs, muscles, and diving behaviors. Different species have evolved for dives of various lengths, but none have developed gills.

Their complex adaptations allow these marine mammals to thrive in an aquatic environment while still surfacing to breathe air when they need to.