The heart of a blue whale, the largest animal on Earth, is also the largest of any animal. A blue whale's heart can weigh around 400 pounds (approximately 180 kilograms) and measure about 5 feet (1.5 meters) in length. 

The size of the heart allows it to pump an enormous volume of blood to sustain the whale's massive body, which can reach lengths of up to 100 feet (30 meters) or more. Each beat of a blue whale's heart can pump up to 220 liters (58 gallons) of blood, enabling it to support the whale's extensive circulatory needs. The size and weight of a blue whale can be compared to several large objects to provide perspective: 

Commercial Airplane

A blue whale's weight is roughly equivalent to that of a fully loaded Boeing 737 or Airbus A320, both of which typically weigh around 70 to 100 tons when fully loaded. 

School Buses

A standard school bus weighs around 12.5 tons (25,000 pounds). So, a blue whale's weight is comparable to that of 8 to 12 school buses. 

African Elephants

The largest land animals, African elephants, weigh up to 7 tons (14,000 pounds). A blue whale's weight is comparable to that of approximately 14 to 20 adult African elephants.