The blue whale, a giant of our earth, can dive up to about 35 minutes and 1000 feet (304.8 m) deep. Nevertheless, normal diving times are shorter to about 5–15 minutes, but still much longer than for most humans. However, blue whales are mammals living in a marine environment, so how do they manage to hold their breath for such a long time? To answer this fascinating question, we have to dive a bit deeper into the anatomy and diving behaviour of these gentle giants!
Respiration in whales
Whales are no fish, they are mammals and this means they do not own gills to breathe underwater, but they still need to surface to breathe fresh air into their lungs. Whales just become perfectionists in holding their breaths for a long time. Depending on the species, time spent underwater varies from a few minutes to several hours!
| Cetacean species | Average dive time (min) | Maximum dive time (min) |
|---|---|---|
| Blue whale | 20 | 36 |
| Sperm whale | 45 | 138 |
| Cuvier’s beaked whale | 60 | 222 |
| Killer whale | 4 | 16 |
And in case you wonder now if whales can drown – no, they have a special mechanism preventing them from drowning, however, if they are unable to surface, they suffocate and die. Usually, suffocation only happens due to entanglement or severe traumata caused by extremely loud noises or pressure.
The blue whale
Undoubtedly, whales are mammoth creatures – and the blue whale exceeds them all. You’d probably think that all the organs in blue whales are extraordinarily huge and thus, they have enormous lungs, which can store more air, resulting in longer dives. However, it’s not that easy! In the following paragraphs, I will explain why and how a blue whale can hold its breath for a long time.
Blue Whale Anatomy
Yes, blue whales own enormous lungs with a capacity of about 5000 liters. However, proportionally their body size, whales have smaller lungs than humans. While a human lung takes up about 7% of the internal body cavity, the lungs of whales only take up about 3% of it. Whale lungs are structured differently, with a series of well-perfuse air sacs connected, making them more efficient. The more important fact, however, is, that blue whales can store up to 90% of their oxygen intake.
All baleen whales usually have two blowholes, facilitating higher oxygen intake. The complete respiratory system of whales is much more efficient than in their land-living ancestors. These blowholes play an important role as they are closed by a small muscular flap during the dive and only open at the surface with a high-pressured exhalation to clear off surrounding water molecules. These molecules are not supposed to enter the connected trachea and lungs. A flexible ribcage further prevents these highly adapted lungs from collapsing under pressure.
Besides big lungs, blue whales also own a huge 200 kg heart, which needs to pump more than 1000 litres of blood through their immense body. Generally speaking, blood takes up to 20% of the body volume in whales, but only up to 7% in humans. But not just this, moreover blood and muscles with their special proteins called haemoglobin and myoglobin, appear to be the main oxygen storages in whale bodies! In each of these proteins, whales possess 30% more than humans, facilitating up to 35% of oxygen storage in whales. In total, whales can store up to 75% of the inhaled oxygen in their circulatory system!
Blue Whale Diving
One of the important conditions of long dives is performed already before diving into the deep abyss. Instead of inhaling and diving, they exhale about 90% of the trapped air at up to 600 km/h before descending. Part of the highly efficient gas exchange in cetaceans is based on this mechanism since stale air gets expelled first and thus, more fresh oxygen can be absorbed. The result is oxygen absorption of about 90% per breath in whales and only up to 15% in humans. Another advantage is that without the air-filled lung, buoyancy is decreased, and sinking affords less movement and energy and thus, less oxygen use.
Dive Response and Underwater Adaptations
Additionally, the so-called dive response in marine mammals helps them to stay underwater for a long time. This mechanism consists of several altered body activities. A good example is the slowed-down heart rate in diving individuals. They can slow it down to about 3 beats per minute. Furthermore, the blood supply to non-essential organs, such as skin and digestion-related organs, is reduced. This mechanism is called ischemia. Some blood pathways are even completely blocked while diving. Here, we can see the importance of resting periods on the surface because prolonging these processes can become harmful to the animal.
On top, anaerobic respiration offers a breathtaking opportunity to stay longer underwater. Usually, most whales start this respiration process after at least 90% of the dive. Due to biochemical processes, lactic acids are built up, decreasing muscle efficiency by muscle fatigue. This situation is similar to our sore muscles after intense training. Using this respiration type earlier may result in problems and exhaustion during the dive. Only beaked whales, the record divers, found a yet-unknown mechanism to deal with these issues. As they are known to dive for up to almost four hours, they may commonly use anaerobic respiration during the last hour of their dive.
Foraging behavior and prey of blue whales
Anyway, the main prey of blue whales consists of plankton, small fish, and krill, which can be found normally in the upper layers of the water column in our oceans. Given the basis that natural evolution favors efficiency and survival (reproduction) success, the blue whale has no obvious reason for diving extremely deep and long. Studies suggest further that the lunge-feeding foraging strategy of blue whales is very energy-consuming and, thus, limits their dive duration. Researchers supported this hypothesis by examining other big baleen whales with different foraging behaviors, which tend to have longer dive durations.
Conclusion
All in all, in this article, we could shed some light on these mystical creatures and their diving behavior. Blue whales are not counted as marathon divers, with “only” up to half an hour spent underwater, but their massive bodies are spectacularly adapted to their environment and truly mesmerizing to watch!
If you want to see these stunning ocean giants up close in real life, your chance is here! Blue whales migrate through the waters of the Azores during springtime, between March and the beginning of June of each year. Just get in touch with us! Book your tour to go out with our knowledgeable biologists from Futurismo and learn much more about these fascinating whales!
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