By Liv Davies
The blue whale is often considered to be the largest mammal that has ever lived. It is on average around 24-30 metres, and weighs in at around 200 tonnes. The heart itself weighs around 400 pounds and is 5 feet long!
A group of researchers at Stanford University have finally measured the heart beat of a blue whale. This mammoth task was produced via sensors attached by two suction pads that were placed near the whales left flipper, and measured the animals heart rate through electrodes. “There were a lot of high fives and victory laps around the lab.” said Jeremy Goldbogen who is the lead author of the research paper at Stanford.
“Animals that are operating at physiological extremes can help us understand biological limits to size,” said Goldbogen, who explained the reasons behind the study – “They may also be particularly susceptible to changes in their environment that could affect their food supply. Therefore, these studies may have important implications for the conservation and management of endangered species like blue whales.”
The researchers had great difficulty placing the sensors on the belly of the blue whale due to the texture of the skin. This species of whales has “accordion-like skin” on its stomach that expands during feeding, and could cause the suction pads to spring off. However, once the pad was stuck, it showed unexpected results.
As the whale dived into the ocean its heart rate reduced to an average of 4-8 beat per minute, and as the whale resurfaced, the heart rate increased around 2.5 times. It must be noted that whales are mammals, and therefore do not have gills, so they must hold their breath whilst they dive and keep oxygen circulating to all part of the body, so having such a low heart rate whilst diving, is an astonishing find.
The researchers found that the highest heart rate was greater than predictions, and lowest heart rate was around 30-50% reduced. This may be put down to the aortic arch being significantly stretchier than most other mammals – this allows the blood pressure to be maintained between beats. Higher rates of beats per minute may show that the whale’s heart is effectively working at it maximal rate for its size, showing that may be predicted to be physically impossible for an animal to be larger than the blue whale.
Atrial fibrillation: Atrial fibrillation is a phasic heart condition that causes an irregular and sometimes abnormally fast heart rate. This occurs because the top quadrants of the heart, the atria are beating faster than they should.
A normal human heart beat is between 60 and 100 beats per minute, however someone with Atrial fibrillation can have a heart rate of up to 100 to 175 beats per minute. This condition can cause stroke and other related heart conditions.