How long can you hold your breath underwater? If you’re not a professional free-diver or a navy seal, chances are you’ll probably reach around a minute or two. While the human record of natural underwater breath-holding lies at an impressive 11 minutes, marine mammals easily beat all the records. Cuvier’s beaked whales are the ultimate champions, with one whale diving almost 3 km and another individual staying underwater for a whopping 222 minutes! That’s 3 hours and 42 minutes – twelve minutes longer than the entire Titanic movie! How do they do it? Let’s dive into the world of the deepest diving whales’ adaptations.
Oxygen adaptations that take your breath away
Over millions of years, whales have evolved adaptations that enable them to out-dive even the most skilled scuba divers. Firstly, they have high blood-to-body-volume ratios, which is essential because blood stores and transports oxygen. Oxygen regulation is necessary during dives because air-breathing animals drown when the body runs out of oxygen. Secondly, relatively high concentrations of red blood cells further help carry oxygen. Thirdly, whales’ muscles contain a lot of myoglobin, a protein that helps store oxygen. A final oxygen-saving trick involves minimizing blood flow to specific organs, stopping breathing, and lowering the heart rate. Weddell seals, for example, are kings of this ultimate relaxation mode – during dives, they can reduce their heartbeats to as little as four beats per minute!
Can they handle the pressure?
Whales are quite literally under a lot of pressure. One kilometer underwater, the body experiences a hundred times the normal amount of pressure. As a result, air-filled spaces such as lungs and ears are at risk of compressing or even collapsing. Yet, even though whales are often in deep waters in the literal sense, they hardly are so figuratively. Clever adaptations help them cope with the troubles of life underwater. For example, whales’ lungs contain two separate parts; one air-filled compartment and another collapsed one. The blood flows mainly through the collapsed part to minimize nitrogen exchange. This is important because too much nitrogen in the blood can cause a narcotic effect and increase the risk of the bends.
The bends: the divers’ disease
When air-breathing animals dive, nitrogen bubbles accumulate in their blood and tissue because of the increasing pressure. If the ascent back to the surface occurs too rapidly, the nitrogen bubbles don’t have enough time to diffuse into the lungs. Instead, they expand in the blood and tissue, resulting in lots of unpleasantness, more formally known as the bends or decompression sickness. Many human divers have suffered from the bends, and even the seemingly perfectly adapted whales are not immune to decompression sickness.
Even whales get the bends?
Usually, whales can avoid getting the bends simply by taking their time to ascend to the surface. However, gas bubbles in the tissues of several stranded whales hint at the possibility of death by the bends even in marine mammals. Scientists suggest that loud noises could disturb whales in their underwater world, sending them rushing to the surface. This implies that for example sonars and oil drills could expose cetaceans to decompression issues… Yet another reason to think twice about noise pollution in oceans. We wrote a post about it, you can find it here.
When will new discoveries come to the surface?
Collapsed lungs, specialized blood compositions, and oxygen storage proteins undoubtedly make whales exceptional divemasters. Even though humans will never parallel cetaceans’ incredible diving capacities, we can still learn a lot from the adaptations that make marine mammals such good underwater breathers. While we get to know more and more about the physiological limits of whales and dolphins, I wonder what new breath-taking features will come to the surface.
- N.J. Quick et al. Extreme diving in mammals: first estimates of behavioural aerobic dive limits in Cuvier’s beaked whales. Journal of Experimental Biology. 2020.
- G.S. Schorr et al. First long-term behavioral records from Cuvier’s beaked whales (Ziphius cavirostris) reveal record-breaking dives. PLOS One. 2014.
- A. Fernández et al. Gas and fat embolic syndrome” involving a mass stranding of beaked whales (Family Ziphiidae) exposed to anthropogenic sonar signals. Veterinary pathology. 2005.
Thank you for reading! Did you enjoy this post? FInd out more about the effect of noise on the deepest diving whales:
Eline van Aalderink is a recent MSc Marine Biology graduate from the University of Groningen (the Netherlands), where she specialised in marine mammal ecology and conservation biology. She is currently working as a marine mammal research assistant/supervisor at Archipelagos Institute of Marine Conservation in Greece.