Two blue whales are swimming up from the ocean
depths. They are blowing bubbles in a tighter and
tighter circle. Suddeniy, one opens its huge mouth
and takes in a massive amount of water. With a
tongue that weighs more than an adult elephant,
lt forces the water out of its mouth. Using a highly
efficient filtering system, it keeps and swallows
hundreds of kilograms of krill. Krlll are the primary
source of food for many whales, and blue whales,
the largest animal on earth, eat about four tons of
krill every day.