Whales are the biggest animals that have ever lived on the planet.  The largest animal in the world is the blue whale.  The biggest recorded blue whale was over 110 feet long, and weighed more than 400,000 pounds.  There are about 80 different kinds of whales.  It would take 30 fully-grown elephants to equal the weight of a blue whale.  The humpback whale has the longest flippers of any whale.  They are about 14 feet long.  Humpback whales can grow to be 60 feet.  The average humpback weighs over 40 tons (8,000 pounds), while an average adult human weighs 200 pounds. The skeleton of a human usually weighs 25 pounds.  The skeleton of a blue whale weighs more than 50,000 pounds.  A large blue whale can eat more than 9,000 pounds of food everyday.  They eat plankton.