What is your definition of a whale? How many BTCs do you need to have to be a whale?
As far as I know Whales are Rich because they own A lot of coins it's like they own the almost 1/4 to 1/2 of the total allocation for all investors and ICO participants. They owned big money in their accounts. It's like 10 BTC is really small amounts for them.
They are the rich one, who are willing to invest higher because they know the potential income that they can get from investing big in it. They are called whales because they are creating big impact about the value of bitcoin, if they buy value gets higher and if they sell the value became low too.