The living animal and the biggest and largest animal in the world is the Blue Whale. Dinosaurs were larger than the blue whale but then they died a long time ago. Blue whales are the largest animal that happen to live in the sea. A Whale is not a fish because it mother gives milk to it baby calf.
Most whales like the blue whale measures 20 meters but others happen to grow 30 meters. The blue whale weighs 250 tonnes!! It is even heavier than a barge!