Which animal is the largest known animal in Earth’s history?

The blue whale is the largest known animal in Earth’s history.

Blue whales can exceed 30 metres in length, and some individuals weigh well over 150 tonnes. Their immense size surpasses that of every known dinosaur and other animal described by science. The heart of a large blue whale can weigh several hundred kilograms.

Despite their size, blue whales mainly eat tiny krill. They take in enormous mouthfuls of water and food, then push the water through baleen plates while retaining the krill. This feeding method allows a blue whale to gain energy from very small prey.

Commercial whaling reduced blue whale populations dramatically during the twentieth century. International protection helped stop most direct hunting, but the species remains endangered. Ship strikes, entanglement, noise, and changes in krill distribution continue to affect populations.