According to National Geographic, blue whales feed on tiny, shrimp-like organisms called krill. A blue whale can consume up to 4 tons of krill each day.
In order to eat these tiny organisms, blue whales have a row of pleated plates, called baleen, attached to their upper jaws. When feeding, a blue whale swims into a large group of krill and opens its mouth, taking in a large amount of water. With its tongue, the whale forces the water out of its mouth, through the baleen plates, which act like a sieve, catching the krill. Blue whales spend the summer months feeding in cold, polar waters, and they travel great distances toward the Equator when winter approaches.
According to National Geographic, blue whales are the largest animals on Earth, able to reach lengths of up to 100 feet and weigh more than 200 tons. Its heart alone weighs as much as a car. Blue whale calves are born weighing 3 tons and, consuming only their mothers' milk, gain about 200 pounds each day during their first year. The average lifespan for a blue whale is 80 to 90 years. It is estimated that between 10,000 and 25,000 blue whales are still living in the wild as of 2014.