Beluga whales do not lay eggs; they give live birth because they are classified as mammals. This Arctic and sub-Arctic species is known for its distinctive white color. Their reproductive method requires internal fertilization, a lengthy pregnancy, and the nurturing of a calf.
Belugas Are Marine Mammals
Beluga whales are warm-blooded vertebrates, requiring them to maintain a consistent internal body temperature in the frigid Arctic waters they inhabit. They possess lungs and must regularly surface to breathe air. The thick layer of blubber beneath their skin provides insulation, a common adaptation among large marine mammals. These biological characteristics place them firmly in the Class Mammalia, defined by features like specialized teeth and the production of milk to feed their young.
Gestation and Calving
The live-birth process begins with a long gestation period, typically lasting between 14 and 15 months, sometimes extending up to 15.8 months. This extended pregnancy allows the single calf to develop significantly before birth. Female belugas generally give birth once every three years, a relatively slow reproductive rate that reflects the investment required for each calf.
Calving usually occurs during the summer months, often between May and September. Births take place in warmer, shallower waters, such as coastal bays and river estuaries, where the water temperature is around 10° to 15°C. These warmer nursery areas are thought to offer protection and a more suitable environment for the newborn, which lacks the thick blubber layer of an adult. The calf is born at a length of approximately 1.5 meters and weighs around 80 kilograms, immediately able to swim alongside its mother.
Nursing and Calf Dependency
Following birth, the beluga calf immediately begins the nursing period, a defining mammalian trait. The mother provides milk through specialized mammary slits while swimming underwater, with the calf suckling at frequent intervals. Beluga milk is exceptionally rich, containing an average of about 28% fat and 11% protein, which provides the high-energy nutrition needed for rapid growth and blubber development in a cold environment.
The nursing period is prolonged, lasting for at least one year and often extending for 20 to 24 months. During this time, the calf is completely reliant on its mother for sustenance and protection, gradually supplementing its diet with small fish and shrimp as its teeth emerge. A calf is born with a dark gray or brownish-gray coloration and does not achieve the pure white skin of an adult until it is around seven to nine years old, marking its full maturity.