Blue whale (Balaenoptera musculus), computer artwork. Blue whales are the worlds largest animals, growing up to 30 metres in length and to a weight of 200 tons. This makes them in all probability the largest animal that has ever lived. They are found throughout the worlds oceans, feeding on small crustaceans called krill, which they filter out of the sea. It requires 34 tons of krill a day to support a blue whale.
