The blue whale's heart is the size of a small car

The blue whale (Balaenoptera musculus) is the largest animal known to have ever existed, reaching up to 33 metres in length and 190 tonnes. Its heart weighs up to 200 kilograms — roughly the size of a small car — and beats just 4–8 times per minute when the whale dives deep. When feeding, a blue whale can consume up to 40 million krill per day (approximately 3,600 kg). Despite its size, its throat is only about 10 centimetres wide — too small to swallow a human. The blue whale's heartbeat can be detected by instruments from over 2 miles away.

Source: Goldbogen et al., Science (2019)