A Mighty Heart For A Mighty Creature
To power their humongous bodies, blue whales are equipped with a huge heart as well. The whales heart is about 5 feet in length, 4 feet in width and 5 feet in height, and can weigh as much as 175 kilograms, which is the same as some cars. A blue whale’s heartbeat is so loud that it can be heard from almost 2 miles away. But thats not the only interesting thing about a blue whales heartbeat. On average, when it is at the surface of the water, the blue whale’s heartbeat is around 25 – 35 beats per minute. However, when it dives deep underwater for food, a blue whales heartbeat can drop to almost 4 – 8 beats per minute, and sometimes even 2 beats a minute. This effectively allows the blue whale to minimise the amount of work its heart does while continuing to distribute blood evenly around the body, even at extreme depths and cold underwater temperatures.
Blue Whale Hearts May Beat Only Twice A Minute During A Dive
Natures most extreme animal has an equally extreme circulatory system, researchers found.
A plastinated whale heart, from a blue whale that died in Newfoundland in 2014, being prepared for shipment in Germany for a museum exhibit.Credit…Bernd Settnik/picture alliance via Getty Image
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Blue whales have a flair for paradox. They live in water but breathe air. Theyre enormous the biggest creatures that have ever lived, as far as anyone knows but subsist almost entirely on tiny krill.
And as new research reveals, even the animals dunk tank-size heart jumps between extremes. In a study , a team of researchers for the first time attached an electrocardiogram tag to a free-diving blue whale to trace its heart rate.
They found that the rate ranged as low as two beats per minute and as high as 37. Such numbers paint a picture of an animal frequently pushing its own limits, and suggest that the whale is not only the largest animal ever, but perhaps as large as an animal with a circulatory system can possibly be.
The data showed that when this whale descended, its heart rate plummeted, too. At the bottom of the dives, the whales heart rate hovered around four to eight beats per minute. At times, it fell all the way down to two.
Placing Electronic Sensors On A Blue Whale
The scientists had previously measured the heart rates of emperor penguins using a tag full of sensors, and they then decided to try out the system in whales.
The team trialed the sensor tag in small, captive whales, and it succeeded. However, applying the tag to a blue whale in the wild was a different feat altogether that entailed various other challenges.
Firstly, people have trained captive whales to flip their bellies up, which allows for easier access. Secondly, the grooves on the blue whales underside enable the large mammal to expand a great deal when feeding, thus making it easy for the tag to detach.
I honestly thought it was a long shot because we had to get so many things right finding a blue whale, getting the tag in just the right location on the whale, good contact with the whales skin and, of course, making sure the tag is working and recording data, Goldbogen explains.
We had to put these tags out without really knowing whether or not they were going to work, says study co-author David Cade, who also placed the tag on the whale. The only way to do it was to try it. So we did our best.
Cade managed to stick the tag from the first try, and four suction cups secured the electronic tag near the mammals left flipper, where it recorded its heart rate.
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Emperor Penguins And Blue Whales
In emperor penguins, beat-to-beat heart rate profiles obtained from the digital ECG recorder during dives reflected the averaged 15-s heart rate profiles found in the earlier study and, importantly, demonstrated the variability and control of heart rate in exquisite detail. Heart rates declined from high inter-dive surface values, initially hovered at near-resting and even below-resting values, and then continued to decrease, sometimes to values as low as 510 beats min1 , as dives became longer and deeper . During ascent, heart rate increased as in other species . Dive heart rate was typically above the resting level for short duration dives, but it progressively decreased as dive duration increased. The dive response of emperor penguins was variable both in the intensity of bradycardia and the degree and pattern of vasoconstriction as evidenced by muscle myoglobin desaturation profiles during dives . During the bottom phases of 400500-m deep dives, heart rates were lowest while wing stroke rates were usually quite high . In these long deep dives, heart rate appeared uncoupled from exercise intensity. More recent papers have also found plasticity in the dive response and have evaluated the potential effects of exercise on heart rate in different types of dives of seals, sea lions, and cetaceans .
Scientists Have Discovered Something Big In The Heart Of A Blue Whale
The first-ever recording of a blue whale’s heart rate reveals why they win the size game — and why they aren’t even bigger.
Blue whales are among the most fascinating creatures on the planet, existing at the limits of what we know to be possible. They are the largest animals to have ever lived on Earth, clocking in at up to 105-feet long and some 200 metric tons . They are also among the loudest-known animals on the planet scientists think that, if ocean conditions are right, blue whales can communicate with another whale 1,000 miles away. Imagine being able to yell from New York and have someone hear you in Tampa. And though they dwarf us humans in so many respects, they can live just as long as we can, averaging 80-90 years.
Their solitary habits, relative scarcity , and sheer size mean that studying blue whales in the wild is difficult.
There is much we dont know about these blue whales, including how their heart works. New research provides some clues about the heart of a blue whale, and like its other features, it seems to be operating at its limits, too.
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The heart of the Etruscan shrew, one of the worlds smallest mammals, beats incredibly fast up to 1,500 times per minute, or 25 times per second. The human heart, in comparison, is sluggish, beating only 60 to 100 times a minute.
Then theres the heart of the blue whale, the largest animal ever to have lived. These marine giants can be longer than two school buses, and their hearts which are roughly the size of a loveseat and weigh over 1,000 pounds beat as few as two times per minute.
If you were to put an enormous stethoscope up to a blue whales chest underwater, it might sound something like this.
That clip was produced using real data that scientists collected a few years ago from a blue whale in Monterey Bay, California. The heart beat slowly when the animal dived, but when it came to the surface to breathe, the rate picked up dramatically, reaching as fast as 37 beats per minute.
In the last few years, scientists have figured out how to listen to the heartbeats of wild whales. Theyre not interested in checking these animals vitals, per se, but trying to answer one of biologys most fundamental questions: How large can an animal on Earth get?
Other Interesting Information About Blue Whales
Even at birth, a baby blue whale is large measuring in at 25 ft long , the baby blue whale can drink up to 150 gallons of milk a day and gain as much as 200 lbs per day in its first year.
To keep its energy up, an adult blue whale can consume as many as 40 million krill per day or 8,000 lbs. of krill daily!
Despite the name blue whale, this actually appears to be closer to a grayish blue coloring.
When you observe a blue whale, the deep blue color is actually because it is submerged underwater, making the whale appear to be a deep blue.
Even though the blue whale is enormous, it has a relatively slender body allowing it to travel up to 30 miles per hour for short bursts when it feels threatened or startled.
The largest confirmed measurement of a blue whale was 109 ft, and the heaviest blue whale weighed an estimated 200 tons.
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How Did Blue Whales Get So Big
The short answer: food. Several million years ago, blue whales evolved to binge-eat tiny crustaceans called krill, which are super abundant in some coastal regions during part of the year. All of that food can fuel a big body, and being big allowed these animals to take larger gulps of krill and swim efficiently from one krill buffet to the next.
But whats interesting is that there are actually enough krill and other aquatic critters in the ocean for the whales to be evenbigger. Food, alone, does not seem to limit the potential body size of whales, said Max Czapanskiy, a doctoral researcher at Stanford who studies marine mammals. There has to be something about their bodies thats keeping them from getting even bigger, he said.
The answer, scientists suspect, may lie in the heart.
Whales hold their breath as theyre feeding on krill, which tend to aggregate hundreds of feet underwater. That causes carbon dioxide to build up in their blood. When these marine mammals return to the surface to breathe, their hearts beat fast to rid their bodies of CO2 and replace it with fresh oxygen, so they can dive back down and continue foraging.
Larger hearts beat more slowly and take longer to replenish oxygen in the body. That means whales have to spend more time on the surface, catching their breath, which eats into precious time they have to feed on a seasonal resource like krill. Too big a heart and these behemoths might not have enough time to eat.
What You Can Learn From A Whales Beating Heart
Heart rate data from the blue whale shows that these animals essentially have two different heart rates. One of them is slow, like the clip you heard above thats when the whale is diving and trying to conserve oxygen. The other is fast, when the whale is back at the surface and its heart is racing to replenish oxygen.
As researchers suspected, its there, on the surface, where big-bodied-ness could become a problem.
The EKG data shows that a single beat of the blue whales heart takes about 1.8 seconds, which means its heart can only beat roughly 33 times per minute. But as the whale was catching its breath, its heart was maxing out slightly above that number. This suggests something critical: The blue whales heart is working at peak performance, Czapanskiy said, and it literally cant beat any faster.
But what does that have to do with the limits of body size? If the whale were any bigger, it would need a bigger heart and more food. But, again, a bigger heart would beat slower and require the animal to spend more time at the surface, giving the whale lesstime to forage for krill. So basically, any bigger, and these animals likely wouldnt be able to consume enough food to sustain their hulking figures.
Thats a theory, anyway.
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State Of The Art In The 1970s
Prior to 1980, most heart rate records during unrestrained breath holds and diving in marine mammals were obtained in animals under managed care with use of bench top ECG recorders attached to long leads or with use of radiotelemetry. Investigations included sea lions, harbor seals , gray seals, dolphins, a beluga , a killer whale , and even a non-marine mammal, the hippopotamus . Apart from an ECG of a harpooned beluga , the only ECG and heart rate data from a wild animal free-diving at sea were partial records obtained in Weddell seals with long, break-away ECG electrodes, and a bench top recorder .
Telemetry research on unrestrained, spontaneous dives of birds at this time primarily focused on ducks in laboratory tanks . Heart rate profiles of hand-reared cormorants diving in a bay were obtained with the use of acoustic telemetry . In Humboldt penguins , radiotelemetry transmitters documented heart rates during dives of up to 50-s duration in a laboratory tank . In the only cardiovascular study of diving birds in the wild during this time period, heart rate was obtained with telemetered arterial blood velocity profiles from a tethered gentoo penguin spontaneously diving in the sea .
Two Beats A Minute Underwater: A Lesson In Blue Whale Cardio
In an uncommon exercise in cetacean research, a team successfully placed a tag with electrodes on the back of a blue whale to calculate its heart rate. The results are staggering: this medium-sized bull with a resting heart rate of around 15 beats a minute can lower it to as little as two! Two beats a minute! Thats a drop of over 85%. In comparison, a human at rest has a heart rate of between 50 and 80 beats per minute and can subconsciously lower his or her pulse by as much as 25% when holding his or her breath. But how is the blue whale able to survive such a low heart rate and, especially, what are the benefits for the animal?
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Whats The Heart Rate Of A Blue Whale We Now Know
Thought to be 70 metric tons in weight, the researchers estimate that the teen whales heart weighs 319 kilograms and pumps out 80 liters of blood with each beat. From that, they predicted the whales resting heart rate would be 15 beats per minute . But the patterns in heart rate they found defied their estimates.
When the whale descended into a dive, its heart rate plummeted to between 4-8 beats bpm, reaching as low as just 2 bpm on one dive a third to a half as much as the resting heart rate predicted. On ascent, the whales heart rate accelerated quickly, maxing out at up to 37 bpm once back at surface, or more than 2.5 fold the predicted rate.
The results suggest something very big indeed: The heart of a blue whale is working at its physiological limits in the course of normal feeding behavior.
This blue whale had heart rates ranging from 2 bpm to 37 bpm, which is more than an order of magnitude difference 10-fold, Goldbogen tells Inverse. In comparison, human heart rates might typically range from 60 bpm to 200 bpm, which is a much lower range, just over a 3-fold difference.
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WASHINGTON Using a bright orange electrocardiogram machine attached with suction cups to the body of a blue whale, scientists for the first time have measured the heart rate of the worlds largest creature and came away with insight about the renowned behemoths physiology.
The blue whale, which can reach up to 100 feet long and weigh 200 tons, lowers its heart rate to as little as two beats per minute as it lunges under the ocean surface for food, researchers said on Monday. The maximum heart rate they recorded was 37 beats per minute after the air-breathing marine mammal returned to the surface from a foraging dive.
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, Goldbogen added. What is life like and what is the pace of life at 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 around the body. The normal human resting heart rate ranges from about 60 to 100 beats per minute and tops out at about 200 during athletic exertion. The smallest mammals, shrews, have heart rates upwards of a thousand beats per minute.
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Scientists Have Recorded The Heartbeat Of A Blue Whale
In a first, researchers have recorded the heartbeat of a blue whale over the course of eight and a half hours in the wild. What they found suggests blue whale hearts are working at their limits just to enable the whale to feed. As a result, these heart limitations may be what is stopping the whale from evolving to be even larger.
The findings were published this week in the journal Proceedings of the National Academy of Sciences.
What they found was something wonderfully big.
To measure the heartbeat of a blue whale, researchers attached an echocardiogram-depth monitor onto the underside of a 15-year-old male blue whales left fin as it swam in the waters of Monterey Bay, California.
The teenage whale is a regular to the bay, appearing there and elsewhere off the coast of California throughout its life. The lunchbox-sized sensor gathered 8.5 hours of data from the whale, capturing its heart rate as it undertook four different feeding dives of up to 16.5 minutes long and down to 184 meters in depth. Just getting the sensor to stay put was a feat in and of itself, the researchers said.
I honestly thought it was a long shot because we had to get so many things right: finding a blue whale, getting the tag in just the right location on the whale, good contact with the whales skin and, of course, making sure the tag is working and recording data, Jeremy Goldbogen, an author on the paper and associate professor at Stanford University, said in a statement.