What is the largest mammal in the world?

The blue whale is the largest mammal in the world.

Blue whales belong to the baleen-whale group and are also the largest animals known to have existed. Adults can reach roughly 30 meters (nearly 100 feet) in length, although size varies by individual and population. Their enormous bodies are supported by a diet of tiny krill rather than large prey.

Despite their size, blue whales feed by filter-feeding. They take in huge mouthfuls of seawater and use baleen plates—comb-like structures made of keratin—to strain out krill. During feeding season, a blue whale may consume several tonnes of krill in a day. Its powerful tail flukes propel it through oceans worldwide.

The African bush elephant is the largest living land mammal, but it is much smaller than a blue whale. Some extinct animals may have rivaled blue whales in mass, but estimates for fragmentary fossils remain debated. The blue whale is therefore the standard answer for the largest living mammal and largest known animal.