Curiosity 9 of 10
9. The blue whale's heart weighs about 180 kilograms
The blue whale is the largest living animal, and its heart matches: one specimen measured in Canada weighed about 180 kilograms. During a dive, this heart can beat only twice per minute.
A heart working at its limit
In 2014, dead blue whales washed up on the coast of Newfoundland, Canada, and the heart of one of them was preserved by the Royal Ontario Museum. It weighed about 180 kilograms, and it took four people to lift it. It is the largest heart in the animal kingdom.
In 2019, a team from Stanford University measured the heartbeats of a blue whale in the wild for the first time, with a sensor attached to the body by suction cups. At depth, while diving in search of food, the heart beat four to eight times per minute, and went as low as two. On returning to the surface to breathe, it rose to as many as 37 beats per minute.
Beating slowly at depth helps conserve the oxygen stored in the body during the dive. At the surface, the heart speeds up to recharge the blood as quickly as possible. The researchers concluded that this heart already works close to its limit, which may be one of the factors that limit the size of whales.
To feed, the blue whale opens its mouth and swallows an enormous volume of water with krill, small crustaceans similar to shrimp, all at once. It then pushes the water out through its baleen plates, comb-like plates it has in place of teeth, and keeps only the food. An adult can eat several tons of krill per day.
Did you know? A blue whale calf is born about 7 metres long and gains weight very quickly in its first months, nursing on milk that is extremely rich in fat.
