Is the blue whale's heart really the size of a car?

There are many rumors that the largest animal on our planet - the blue whale - has a heart the size of a car, but this is not necessarily true.

In 2015, a dissection of a blue whale that was stranded in Canada revealed that many of our previous assumptions about the size of the whale's internal organs were wrong. This may be because we have had few opportunities to measure the actual size and weight of the whale's internal organs.

A popular belief is that the heart of a blue whale is the size of a car (often compared to a Volkswagen Beetle) and weighs half a ton. However, the actual size is about the size of a playground bumper car. The heart of a blue whale also weighs about the same as a medium-sized motorbike – about 180kg.

The blue whale (Balaenoptera musculus) is the largest animal that has ever lived on Earth. The largest blue whales can reach up to 34 m in length, and their skulls account for nearly a quarter of their bodies. Blue whales belong to the family Balaenopteridae, which includes humpback whales, fin whales, Bryde's whales, sei whales, and minke whales. Balaenopteridae are believed to have split from other families of the suborder Mysticeti around the middle of the Oligocene (28 million years ago).

Scientists have since replicated the heart of a blue whale and created a replica that is now on display at the Royal Ontario Museum, standing 1.5 metres tall – and it remains the largest heart ever known.

Another popular idea is that the blue whale also has incredibly large blood vessels, and that an adult human could swim through the largest blood vessel in a blue whale. However, this is also a false claim, because in reality, the largest blood vessel (the aorta) in a blue whale is only about the diameter of an adult human head.

However, the blue whale still has many things that make us feel amazed, such as the mouth of an adult blue whale can hold 90 tons of sea water, the tongue alone weighs 2.7 tons, heavier than 3 Volkswagen Beetles.

The blue whale is the largest animal known to have ever lived on Earth. One of the largest dinosaurs of the Mesozoic Era, Argentinosaurus, weighed only 90 tons, which is about the same as an average blue whale.

The sound produced by the blue whale is also incredibly loud (up to 190 decibels, while the noise produced by a jet engine is only around 140 decibels); although humans cannot hear the sounds produced by the blue whale with their ears because these noises are all at frequencies lower than the human ear can hear, in fact, it can travel hundreds of kilometers across the ocean floor.

However, contrary to many people's predictions, the sound of the blue whale can still only rank second in the animal kingdom. The first place belongs to a small species of pistol shrimp in the family Alpheidae , which can emit sounds of 200 decibels.

The mantis shrimp was first discovered after a taxonomic study on a mantis shrimp species of the genus Alpheus from Japan and the Gulf of Thailand.

One would assume that, as the largest animal on Earth, the blue whale would be a predator and eat other large animals. However, in reality, the blue whale's throat is only about 23 cm in diameter. And the blue whale's main diet is krill (shrimp-like crustaceans that average 5 cm in length) and occasionally small copepods (mostly just 1 to 2 mm long).

Blue whales use the sprinting and swimming method to hunt , after diving to a certain depth, they turn around and accelerate to sprint upwards, swallowing a large amount of mollusks above, then use the baleen to filter the seawater and food.

A single blue whale can consume 2 million kilograms of food (equivalent to 500,000 calories) in one sitting. At certain times of the year, blue whales can consume nearly 4 tons of food per day. This sprinting hunt may be the 'largest biomechanical event on Earth.' While blue whales eat huge amounts of food in the summer, they eat almost nothing when they migrate to warmer waters in the winter.

Blue whales typically dive down to 100m to feed during the day, while at night they spend most of their time near the surface. They can typically hunt continuously for 10 minutes without resurfacing, however, there have been recorded cases of continuous dives of up to 21 minutes.

Blue whales have a large, long, slender body that helps them move through the water. They have a smooth blue-gray stomach and a lighter belly, and a series of folds on their neck that can expand four times when they eat.