Adventure Lab: World’s Deepest Diver
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One of the best sources for the coolest, and quirkiest, scientific news is Henry Fountain's Observatory column for The New York Times. It comes out weekly in Science Times, one of the last big concentrated science sections in a major paper. This week he called out an interesting study that suggests elephant seals may rest, or even sleep, while they dive. Picture a dead leaf falling off a tree and floating to the ground. It's a great way for the seals to increase efficiency as they may spend up to 90 percent of their time in the ocean diving.
While the elephant seal may have the easiest time diving, it raises the question: What animal dives the deepest?
Herbert Nitsch vs The Sperm Whale
You can maybehold your breath for two minutes. Nitsch tops nine. The “Flying Fish” works asan airplane pilot and dives in his off time—training and competing enough tohave set 25 world records in seven of the eight freediving disciplines during his career. His goal by 2010, is to freedive to 300 meters, or 1,000 feet.
While the average person has a lungcapacity of four to five liters, a trained freediver can double that. Nitschtrains weeks ahead of a world record attempt by staying underwater forincreasing periods of time at increasing depths. While the average person’sheart rate may slow when their face hits cold water, Nitsch has gone a stepbeyond. “He’s so adapted when he takes out his wet suit and smells thatneoprene his heart rate starts to drop,” says Grant Graves, the former vicepresident of AIDA North America.
As hedescends, the ocean adds 14.7 pounds of pressure per square inch every 33 feet.Blood moves from his extremities to his internal organs. His spleen contractsand forces oxygen-carrying red blood cells into his blood stream. His heartbeatslows more to save oxygen. All the while pressure causes his lungs to contract. During his 2007 world record No Limit depth of 214 meters (or roughly 700 feet), his lungs were something like the sizeof tangerines.
Nitsch constantly has to check hishead because his body is sending his brain confusing messages on gas levels. As his lungs shrink his body tells his brain that it has more oxygen than it actually does, because of the increased concentration in a small space. Nitrogen is squeezed out of his lungs and intohis bloodstream. At extreme depths it can cause nitrogen narcosis, a drunken state affecting judgment. Afterreaching depth and then turning towards the surface his lungs expand. Lower concentrations of oxygen and higher concentrations of carbon dioxide in expanding space may triggerpanic and cause convulsions. Even an experienced diver like Nitsch can black out fromshock, or from an actual lack of oxygen. “It is one of the only sports where ifyou screw up you will go unconscious,” said Graves.
At the least, a professionalfreediver may suffer dizziness at the surface. At the worst, he or she cansuffer a heart attack and die.
You can follow Nitsch this month at the 2009 Freediving World Championships on his blog at herbertnitsch.com.
Yell“Marco” with a sperm whale and you may wait an hour for the spout “Polo.” Thedeepest suspected dive from a scientific paper is quoted at “possibly 2000 meters.”
“It ranks, with the bottlenose whale, other beaked whales and the elephant sealas one of the deepest, if not the deepest diver,” said Woods Hole researchspecialist Michael Moore.
Beakedwhales appear constantly in news headlines for beaching in possible association with sonar use.Elephant seals may dive while they rest. Historically, sperm whales inspired the most fear. During the whaling boom they burst up from the depths, spearing ships into splinters and inspiring epic American fiction and non-fiction.
As sperm whales torpedo down their headcavities fill with liquid and their lungs collapse to prevent pressure ruptures. Oxygen stored in blood and muscle, atlevels four and ten times higher than humans, allows them to stay under longer.
Though their time underwater andat maximum depth dwarfs human records, sperm whales are not impervious to physical problems caused by diving. Tissue damage recovered from stranded cetaceans may indicate they could suffer from something like decompression sickness. Bubbles found trapped in whale bonessuggest they may have to manage something like the bends too.
“What our assumption implies is that sperm whales, along likely with many othermarine mammals, manage decompression issues behaviorally as much asanatomically,” said Moore referencing a 2004 paper published in Science. “Recent reports of atypical beaked whalestrandings associated with intensive sonar use make me speculate that this mayreflect a side effect of those animals being unable to manage dive behavior toavoid bends issues, when under sever acoustic stress.”
In other words, like Nitsch many species of whales may have tokeep a cool head when they dive. For beaked whales, navy sonar may besomething more than a bothersome underwater “noonan.” Though it may not directlycause tissue damage, current thinking is that it may annoy or disrupt whales enough to cause a change in normal diving behavior.
Scientists have been unable to find outexactly what is happening because it is hard to conduct experiments on whales due to their size and the depths at which they travel. Still, new technologies are helping them get closer to an understanding of their behavior. Nature published a story this week about anautomatic underwater glider dispatched to pick up the calls of beakedwhales near Hawaii. And the Honolulu Star Bulletin published a story about scientists tracking beaked whales with satellite tags.
The Winner: The Sperm Whale. Though Nitsch keeps setting higher and higher goals (that he accomplishes), the Sperm Whale has him in time under water.
Note: Interviews conducted previously for a magazine article that did not run.