WhaleTimes gets this question often, so we thought we'd make the answer available for every one. Hope it helps, Jake, the SeaDog
Whales and other marine mammals have special adaptations that allow them to hold their breath longer than a person. Believe or it not, though, breath holding isnt the key -- oxygen conservation and storage is. Seals have so much oxygen in their body, you might be surprised to learn they actually exhale before they dive!
Some of the ways marine mammals conserve or store oxygen include:
|Reduced heart rate: When a marine mammal dives its heart rate slows down to conserve oxygen. Some drop from 120 beats per minute to 4 to 6 beats.|
|Carrying oxygen: Marine mammals have a high concentration of oxygen-carrying cells in their muscles and blood.|
|More blood equals more oxygen: Marine mammals have two to three times more blood than a human. Other adaptations also include a network of spiral blood vessels that act as reservoirs for oxygen rich blood. And, seals and sea lions store oxygenated blood in their extra-large spleen (which can be 45% of their body weight).|
|Recirculating the blood: For extended dives the blood is shunted or recirculated to only the most essential organs, like the heart, lungs, and brain. How long a marine mammal stays underwater depends on the species, where it lives, and what it eats.|
Here are some examples of average diving times: A male Northern elephant seals dive is about 20 to 35 minutes, a harbor seal -- 3 to 7 minutes, and a walrus -- 10 minutes. A bottlenose dolphin may stay under 8 minutes, a killer whale 10 minutes, an Amazon river dolphin can stay under only 2 minutes.
Tidbit: Seals diving capabilities are often underestimated. The breath holding ability of most seals is greater than most whales.
Citation: Musgrave, Ruth A. How can marine mammals hold their breath for so long? Fishin' for Facts. WhaleTimes, Inc. (whaletimes.org) 2011
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