WASHINGTON (Reuters) – Using a bright orange electrocardiogram machine coupled with suction cups to the body of a blue whale, scientists first measured the heart rate of the world's largest creature and discovered the physiology of the renowned giant.
Researchers at Stanford University's Goldbogen Lab, Cascadia Research, Scripps Institution of Oceanography, and the University of California Santa Cruz place a suction label on a blue whale as part of research to measure the animal's heart rate in an undated photo taken. in Monterey Bay, California, USA, courtesy of Goldbogen Lab / Duke Marine Robotics and Remote Sensing Lab / NMFS Permit 16111 / Brochure via REUTERS.
The blue whale, which can reach 30 meters in length and weigh 200 tons, slows its heart rate to just two beats per minute as it moves beneath the ocean surface in search of food, researchers said on Monday. The maximum heart rate recorded was 37 beats per minute after the marine mammal breathed air back to the surface after a dive for food.
"The blue whale is the largest animal of all time and has long fascinated biologists," said Stanford University marine biologist Jeremy Goldbogen, who led the study published in the Proceedings of the National Academy of Sciences.
"In particular, new measures of vital rates and physiological rates help us understand how animals function at the upper end of body mass," Goldbogen added. "What is life like and what is the pace of life on such a large scale?"
Generally speaking, the larger the animal, the lower the heart rate, minimizing the amount of work the heart does while distributing blood throughout the body. Normal resting human heart rate ranges from about 60 to 100 beats per minute and reaches about 200 during athletic exertion. The smallest mammals, shrews, have heart beats above 1,000 beats per minute.
The researchers created a label device, wrapped in an orange plastic shell, that contained an electrocardiogram machine to monitor the heart rate of a whale swimming in the open ocean. The device had four suction cups to allow it to be attached to the whale noninvasively.
The researchers obtained nine hours of data from a 22-meter-long adult whale found in Monterey Bay off the coast of California.
“First, we need to find a blue whale, which can be very difficult, because these animals span vast swaths of the open ocean. Combining many years of field experience and a little luck, we positioned a small rigid hull inflatable boat on the left side of the whale, ”said Goldbogen.
“We have to deploy the label using a six meter (20 ft) long carbon fiber pole. As the whale comes to breathe, we mark the whale in a location we find closest to the heart: just behind the whale's left fin, "Goldbogen added.
Blue-like whales, despite their immense size, feed on small prey. As filter feeders, they bring huge amounts of water to their mouths and prey, including shrimp krill and other zooplankton, using keratin bale plates, the same material found in nails.
During feeding dives, the whale exhibited extremely low heartbeats, usually four to eight beats per minute and as low as two. After emerging to breathe after foraging dives, the whale had a heart rate of 25 to 37 beats per minute.
Will Dunham report; Editing by Sandra Maler
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