Cetaceans breed seasonally, usually in warm tropical waters, and females usually have one calf every 1-3 years. The gestation times range from 9-18 months. Whale calves can swim at or soon after birth. Mother whales care for their young for an extended period of time, usually at least a year, feeding them milk and protecting them. Young cetaceans are frequently mottled in color, camoflaging them from predators.
Newborns have a sparse covering of hair which they lose as adults.
The humpback's song can last for 30 minutes. The songs are thought to be used in attracting mates, to keep track of offspring, and for the toothed whales, to locate prey.