Top of Page Offspring Females reach sexual maturity at about the age of nine. Males reach sexual maturity between ages 9-20. Gestation period for pregnant whales is 16 months. Baby whales are called calves. The mother usually stays with her calf for about a year.
Females have special breast muscles that pump milk into the offspring's mouth.
Whale s milk is very thick and rich and has a lot more fat, protein, and minerals than mammals that live on land. Because the milk is so nourishing, baby whales grow very fast. Some blue whales can gain up to 200 lbs. per day. Sperm whales live up to about 60 years old.