The blue whale (Balaenoptera musculus) is the largest known animal ever to live on sea or land. Individuals can reach more than 33 metres (110 feet) and weigh nearly 180 tonnes (200 tons). This is more than the weight of 50 adult elephants!
The blue whale's blood vessels are so big that a full grown trout could swim through them to its heart, which is the size of a small car.
Blue-grey in color, with light grey mottling, they're long and streamlined, with a very small dorsal fin and long, thin pectoral flippers. Blue whales are sighted near California's Channel Islands.