Did you know? The blue whale is the largest animal ever to have lived on Earth! £$%^&*! A blue whale can reach up to 25 - 30m long and can weigh well over 150 tonnes. They feed on krill, a sort of tiny shrimp, but because the krill are so tiny and the whales are so massive they require huge quantities of the krill to stay alive. They do this by opening wide their enormous mouths and their underbellies balloon out as they envelop thousands of krill all at once (along with tremendous quantities of water). In one mouthful a blue whale can consume up to half a tonne of krill and 100 tonnes of water. The water is then sifted out through their long brush like teeth called ‘baleen’ and the krill are ingested. If successful this process is an incredibly efficient way of obtaining energy and may be one of the reasons why these whales are able to grow to such an immense size.