Federal endangered species Description Humpback whales are baleen whales, with stocky bodies and flat, broad heads. Full-grown males average 42 feet in length and weigh about 25 tons. Females are larger, averaging 45 feet in length and weighing about 35 tons.
Grooves run along the underside of humpbacks from their chins to their navels.
Their upper bodies are black or blue-black. Their flippers, grooved undersides, flanks, and underside of the flukes can be white or black, depending on geographical race and individual variation. Their flippers are long and wing-like with bumps on the front edges on which barnacles grow. They have paired blowholes on the midline of their heads. Their tail flukes are large, notched, and have an irregularly shaped edge.