The blue whale lives in the ocean. They are the biggest of all whales. They like to eat plankton and krill. Even though they are big they eat tiny things. They move by using their flippers and their tail. They swim very fast. They can be up to 80 feet long. They breathe through lungs just as we do so they have to come up for air. They are mammals, but they are cold blooded. Their body is the same temperature as the water. They have two blowholes. Their heart is about the size of a Volkswagon bug car. The females are larger than the males. Blue whales live about 35 – 40 years. There are about 10,000 - 14,000 blue whales in the world. Blue whales are an endangered species because they were hunted for their meat, oil and other body parts which were very valuable. They have a small sickle shaped dorsal fin. They live in pods which are small groups. Sometimes they swim in pairs.