Using a bright orange heart rate machine attached with suction cups, scientists have achieved the incredible feat of measuring the heart rate of a blue whale in the wild.
Until now, scientists could only record what they saw and heard as the world’s biggest species dived, swam, foraged* for food and came to the surface to breathe.
“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 journal Proceedings of the National Academy of Sciences.
“In particular, new measures of vital* rates and physiological* rates help us understand how animals work at the upper extreme of body mass*,” Dr Goldbogen added. “What is life like and what is the pace of life at such a large scale?”
Blue whales can reach up to 30m long and weigh about 180 tonnes.
Generally, the larger the animal, the lower the heart rate, minimising the amount of work the heart does while distributing blood around the body.
The heart rate machine – called an electrocardiogram – showed the scientists that the whale’s heart rate lowered to as little as two beats a minute when it lunged under the ocean surface for food.
The maximum heart rate they recorded was 37 beats a minute after the air-breathing marine mammal returned to the surface from a foraging dive.
The normal human resting heart rate ranges from about 60 to 100 beats a minute. Extreme physical stress (such as sprinting) can push a human heart rate to about 200 beats a minute.
Children have a higher resting heart rate than adults.
The smallest mammals, shrews, have heart rates around 1000 beats a minute.
Measuring a blue whale's heartbeat
The researchers created a tag device, encased in an orange plastic shell, that contained an electrocardiogram machine. The device had four suction cups to suck onto the whale without harming it.
The researchers recorded about nine hours of information from an adult male whale about 22m long encountered off the Californian coast in the US.
“First we have to find a blue whale, which can be very difficult because these animals range across vast swathes* of the open ocean. By combining many years of field experience and some luck, we position a small, rigid-hulled, inflatable boat on the whale’s left side,” Dr Goldbogen said.
“We then have to deploy the tag using a 6m-long carbon-fibre pole. As the whale surfaces to breathe, we tag the whale in a location that we think is closest to the heart: just behind the whale’s left flipper,” he said.
Baleen whales such as blue whales feed on tiny prey. As filter feeders, they take huge amounts of water into their mouths and strain out krill and other zooplankton*.
During feeding dives, the whale’s heart rate was typically four to eight beats a minute and as low as two.
After surfacing to breathe following foraging dives, the whale had heart rates of 25 to 37 beats a minute.
MEASURE YOUR HEART RATE
You don’t need any medical equipment to measure your own heart rate, just a watch or timer that can count seconds.
Count the beats of your pulse in a minute, which is the same as your heart rate.
Find your pulse by gently placing the pads of your pointer and middle finger flat on your skin either inside your wrist (just to the thumb side of the ropy tendons you can see sticking out from the surrounding skin) or on the side of your neck (about 1-2cm below the corner-shaped bit of your jawbone).
Gently rest your fingers in one spot, wait for a few seconds and if you can’t feel your pulse beating, move your fingers slightly. You may have to try several times until you can feel your pulse.
- foraged: searched for
- biologists: scientists who study living things
- vital: essential, necessary; often used to mean essential body functions like heart rate
- physiological: the type of science relating to living things and how they function
- mass: weight
- swathes: broad or large areas or land
- zooplankton: marine creatures that can’t swim but are swept along in currents
- Where was the whale when they were recording?
- What does a blue whale eat?
- What was equipment was 6m long and what was it used for?
- What was the heart rate of the whale after surfacing to breathe?
- Was it easier to find your pulse on your neck or your wrist?
LISTEN TO THIS STORY
1. Think about it
In the story, you have read: “the larger the animal, the lower the heart rate.” Why do you think that different-sized animals have different heart rates? Write down as many reasons that you can think of.
Time: allow 15 minutes to complete this activity
Curriculum Links: English, Science
Follow the instructions in today’s story to monitor your heart rate for 30 seconds while you are sitting down. Write down your heart rate for one minute by multiplying your count by two. Then try recording your heart rate after doing different activities like walking around, running, singing, doing something exciting and also doing some slow relaxing breathing. Use the information to write sentences explaining how different activities affect your heart rate.
Time: allow at least 60 minutes to complete this activity
Curriculum Links: English, Science
With a partner see if you can identify all the doing words/verbs in this text. Highlight them in yellow and then make a list of them all down your page. Now see if you and your partner can come up with a synonym for the chosen verb. Make sure it still makes sense in the context it was taken from.
Try to replace some of the original verbs with your synonyms and discuss if any are better and why.
HAVE YOUR SAY: What did you find most interesting about this story? Was it about whales or about your heart rate?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.