Add Yahoo as a preferred source to see more of our stories on Google. Just a blue whale's tongue weighs as much as an adult elephant. But what caused blue whales to grow to such an extraordinary size?

A blue whale calf with its mother near the coast of island Pico (Azores)© tane-mahuta/iStock / Getty Images Plus via Getty Images "The blue whale is the largest and loudest animal on Earth." The blue ...

People often think of all whales as giants of the sea when in fact they vary in size dramatically, from the 30-metre blue whale to the two-metre dwarf sperm whale. However, almost all of the largest ...