The blue whale is the largest mammal on earth. This species reaches lengths of 100 feet long and weighs up to 200 tons. The blue whale is believed to be the largest mammal ever to exist on earth.
The blue whale is also the loudest animal on earth. The sounds it makes reach around 180 decibels, and blue whales can hear each other across a distance of 1,000 miles. Although this is the largest mammal, it eats some of the smallest organisms, consuming up to four tons of krill every day. Newly born blue whale calves stretch to 25 feet and weigh 3 tons. These monster-sized animals live an average of 80 to 90 years, though the oldest is thought to have been around 110 years old.