The blue whale is the largest animal that ever lived on earth. An average blue whale is between 75 and 80 feet long, and weighs about 110 tons. Females are larger than males of the same age, the largest perhaps weighing as much as 150 tons. The blue whale feeds almost exclusively on small, shrimp-like creatures called euphausiids or krill. During the summer feeding season, a blue whale consumes an astounding 4 tons or more each day. Blue whales are found in all oceans of the world. In the past, blue whales were subject to harvesting pressures and their numbers declined. Blue whales were given worldwide protection in 1966 and are recovering slowly.