A blue whale may be more than 100 feet (30 meters) long. It can weigh 150 tons or more. Its body is blue-gray, with lighter gray splotches. On the throat and chest are 80-100 long grooves. Whales may look like fishes, but they are mammals. They breathe air and produce milk for their young. Whales love to sing! They use this as a call to mates, a way to communicate and also just for fun! After a period of time they get bored of the same whale song and begin to sing a different tune.