What is the largest animal to have ever lived on Earth?

The largest animal to have ever lived on Earth is the blue whale, Balaenoptera musculus. It is larger than any known dinosaur, land animal, or other confirmed living or extinct animal.

Blue whales are baleen whales that filter-feed mainly on krill. During feeding, they engulf enormous volumes of seawater and push the water back out through baleen plates, trapping their prey. Their size is supported by a highly efficient feeding strategy and the extraordinary productivity of krill-rich oceans.

The longest reliably measured blue whales have reached about 33 meters, while the heaviest scientifically documented individual weighed roughly 190 tonnes. Females are generally larger than males. A blue whale’s heart can weigh around 180 kilograms, and its low-frequency calls can travel vast distances through the ocean.

Some fossil animals have been proposed as possible rivals, including the extinct whale Perucetus and certain giant ichthyosaurs. However, those estimates rely on fragmentary fossils and have been revised substantially. The blue whale remains the standard, best-supported answer for the largest animal ever known.