Blue whales are the largest animals on our planet. An adult blue whale may weight more than 150 tons, which is more than the weight of an ordinary house or cottage! No wonder all the parts of a whale's body are that heavy and large in size. An enormous heart pumps about 10 tons of blood through the massive blue whale body. A blue whale aorta (the main blood vessel) alone is large enough for a human to swim through it. And an African elephant, the largest land animal, can easily fit in the whale's mouth!