They eat krill, the small shrimp (ish) marine invertebrate, or crustaceans that swim through out the oceans of the world. For more details, please see sites listed below.
They don't because then they will have no energy and then die.
Yes, they have to have food to survive.
the sea
They use their giant mouths.
Blue whales are carnivores, although they only eat very tiny things, no bigger than your pinky finger. Their favorite food is krill, or shrimp-like euphausiids, that are up to three inches long. Blue whales must eat two to four tons of krill a day during the feeding season to survive the rest of the year.
You're thinking of Antarctic Krill, Euphasia supberba, the base of the food chain in the Southern Ocean that surrounds Antarctica.
Blue whales are ocean dwelling mammals, they need the water to support their body weight, and for their food. The possibility of blue whales going into Mt Everest is 0.
Blue Whales communicate when they are in long distances and they want to navigate, detect food and predators attract, mates and maintain social blond,
{| ! colspan="5" | The Food Chain of a Blue Whale | Blue whale Zooplankton Phytoplankton |}
North Pacific Right Whale, North Atlantic Right Whale, Blue Whale What he/she means is that the whales in the North Pacific and North Atlantic and the blue whales are endangered because either they can't find enough food, or they are being illegally hunted.
Some whales are at the top of their food chain. While others, like the Blue Whale and the Humpback, are eaten by many Japanese.
Blue whales are consumers. They eat other animals or fish. They don't eat, usually, left over food. And they do not eat dead and decomposed animals like earthworms do.