The blue whale is the biggest living animal in the world. It grows up to 30 metric lons, and the largest can weigh more than 180 metric tons. The tongue pf a blue whale alone can weigh as much as an elephant, and its heart can be the size of a small car. A baby blue whale weighs up to 2.7 metric tons when it is born, and gains 91 kilograms every day for its first year. But these enormous animal can swim ata fast speed of 32 Kilometers an hour.