A blue whale will most likely eat about 4 tones of foods a day. Blue whales feeding habits include krill and plankton. In fact, the krill, a type of ocean creature, is the most preferred meal of blue whales. And since these mammals like krill so much, they can eat up to 10 tones of krill a day. Specialists say that the stomach of blue whales can hold more than 1,000 kg of foods.