Natures wonders: dolphin lungs avoid the 'bends' (Introduction)

by David Turell @, Friday, July 10, 2015, 18:43 (1503 days ago) @ David Turell

When human deep dive the lungs are kept under pressure, and they have to decompress slowly to avoid the 'bends' upon coming to the surface. Dolphins have fully compressible lungs and avoid the bends problem. They can inhale and exhale much more volume of lungs than humans:

"Unlike humans, dolphins do not need to be strapped to an oxygen tank to achieve their impressive diving feats. This is because dolphins have compressible lungs that help them withstand high pressures deep in the ocean.

"'The deeper [dolphins] go into the ocean, the smaller the volume of gas or air in the lungs gets," said study lead author Andreas Fahlman, a professor of biology at Texas A&M University in Corpus Christi. Fahlman found that dolphins can replace as much as 95 percent of the air in their lungs in a single breath. For comparison, humans are capable of replacing only as much as 65 percent. Dolphins exhale and then inhale above water before diving back down with lungs filled with air — each breath consumes and releases a certain amount of oxygen that energizes the animals as they swim the ocean.

"When trainers had dolphins breathe as hard as they could, in breaths researchers called "chuffs," the animals could inhale 8 gallons (30 liters) of air in one second, and exhale 34 gallons (130 liters) of air per second. A human's strongest exhale moves at a rate of 4 gallons (15 liters) per second, and human coughs range from about 10 to 16 gallons (40 to 60 liters) per second. In other words, dolphins move air two to three times faster than humans could ever do, Fahlman said."

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