The heart of a blue whale, which can weigh in excess of 1,300 lbs (590 kg), is the size of a small car. The gigantic heart beats 8 to 10 times per minute, and each heartbeat can be heard from over 2 miles (3.2 km) away. Their arteries are so large that a full adult-sized human can swim through them. At birth, a baby blue whale is already 25 ft long (the size of an adult killer whale) and can drink up to 150 gallons (568 liters) of milk a day, gaining as much as 200 lbs (90 kg) per day in its first year. They feed almost exclusively on krill, which are small, shrimp-like invertebrates that are on average only 1 or 2 centimeters long. They eat 4 to 6 tons of krill a day. As adults, they can grow up to 110 ft (33 m) in length and weigh up to 180 tons. It's fascinating that throughout history, Earth has been home to some of the biggest animals, but the largest one of them all exists in our timeline, swimming in the deep ocean right now.