CORPUS CHRISTI, Texas – It has always been a mystery to researchers, how marine mammals have been able to escape the damaging effects of high pressure as they dive into deep ocean waters, until now.
Dr. Andreas Fahlman, Assistant Professor of Science and Engineering at Texas A&M University-Corpus Christi, and a team of collaborators from Dolphin Quest Oahu, have
discovered that the bottlenose dolphin has extremely compressible lungs which collapse to protect them from damage when diving.
“The dolphins are the true champions of respiratory physiology,” said Fahlman. “The maximal flow rates are at least twice and probably three times higher than those in the terrestrial champion, the horse.”
Every air-breathing marine mammal faces a multitude of challenges as it dives beneath the waves. Carbon dioxide and nitrogen accumulation in the blood can cause intoxication and decompression sickness, while low internal pressures in rigid lungs can force blood into the delicate airways. Yet, whales, dolphins and seals rarely seem to suffer these ill effects.
However, there was little evidence to support the assumption and Fahlman was repeatedly told that the measurements couldn’t be made because of the incredibly high flow rates generated by exhaling dolphins.
That was until Fahlman met Micah Brodsky, a Consultant and Wildlife Veterinarian with an interest in mechanical engineering. Brodsky decided to design a small and portable pneumotachometer, or air flow meter, that could be used to measure dolphin respiration and would survive corrosive salt water.
After nine months of development, Fahlman and Brodsky traveled to Dolphin Quest Oahu, to work with bottlenose dolphins.
Fahlman recalls that the sympathetic relationship between the dolphins and their trainers was also essential for their success. However, even though the dolphins were trained to respond to their trainers’ directions, they only participated voluntarily. Fahlman says this allowed them to test important physiological variables with no stress to the animals.
Placing the pneumotachometer over each dolphin’s blow hole as it waited patiently in the water, they measured the airway pressures and airflows as the animals breathed normally and heavily. They were impressed to see the dolphin’s flow rates of inhalation and exhalation.
After the team analyzed the airflows, they realized that the animals could exchange almost all of the air in their lungs in a single breath. A full article on Fahlman’s discovery has been published in the July 8 edition of “The Journal of Experimental Biology,” Vol. 218, Issue 13.
Fahlman explains that measurements like this could directly impact dolphin health as well as the health of cetaceans – marine mammals including whales, dolphins, and porpoises.
“Lung function testing may be a novel way to investigate respiratory health of cetaceans under human care and we may be able to provide real-time information about oxygenation state and how animals are doing during a mass-stranding to help save animals,” said Fahlman.
Fahlman is keen to study other cetaceans to learn more about their respiratory physiology and the effects of beaching on stranded animals.