Male Humpbacks average 40 to 48 feet, with females ranging from 45 to 50 feet in length. They weigh anywhere from 25 to 40 tons. Their heads take up about one third of their body length and their most recognizable trait, their long flippers run from one quarter to one third the length of their bodies. They reach sexual maturity at age 6 to 8 years, with females giving birth every two to three years to calves weighing up to one ton and 10 to 15 feet long.
Calves feed on mother's milk for a year before being weaned.
They eat krill and small fish such as herring, up to one and one half tons per day. Then a few whales lunge up the middle of the net with their mouths open wide, shoveling the gathered fish in and breaking the surface with their catch. Humpback whales are dark colored on top, but underneath their huge tail flukes a pattern of white and black markings can be seen. Because they lift their flukes before diving, photographs of these patterns are used for identification purposes. Humpback whales are more solitary than many types, joining into groups mainly for feeding and breeding purposes.