Kangaroos raise their young in a unique way. A baby kangaroo, called a joey, develops primarily inside its mother’s pouch after a very short gestation period. This specialized process allows the joey to continue developing in a protected environment.
The Astonishing Size at Birth
A newborn joey is incredibly small and undeveloped. At birth, it measures only about 1 to 2.5 centimeters (approximately 0.4 to 1 inch) long and weighs less than a gram. This tiny, hairless, and blind creature is born after a gestation period of only about 28 to 33 days. Despite its underdeveloped state, the joey possesses strong forelimbs and an innate sense of smell. Immediately after birth, it instinctively uses these developed forelimbs to crawl unaided through its mother’s fur to reach the safety of her pouch.
Growth and Development Within the Pouch
Once inside the pouch, the joey attaches firmly to one of its mother’s teats, which swells in its mouth to ensure a secure connection. The mother provides specialized milk, its composition changing to meet the joey’s evolving nutritional needs. The pouch serves as a warm, protective nursery.
During the initial months, the joey remains almost permanently attached to the teat, focusing on rapid growth. Its eyes open after a few months, and fine fur begins to grow. This sheltered development within the pouch typically lasts for about 6 to 11 months, depending on the kangaroo species.
Life Outside the Pouch and Continued Growth
Around six to eight months of age, the joey begins to make short exploratory trips out of the pouch. These initial excursions are brief, allowing the joey to develop its muscles, practice hopping, and accustom itself to the outside world. The joey will frequently return to the pouch for warmth, protection, and to nurse.
By approximately 8 to 11 months, the joey leaves the pouch permanently, although it may continue to put its head inside to suckle for several more months. Red kangaroos typically leave the pouch around eight months, while grey kangaroos may stay until about 11 months. Even after fully emerging, joeys remain dependent on their mothers for milk and guidance, sometimes continuing to nurse until they are 18 months or even two years old. At the time of permanent pouch departure, a joey can weigh around 5 to 7 kilograms (11 to 15 pounds), which is roughly 20% of its mother’s adult weight. They continue to grow and mature, eventually reaching full adult size and independence around 15 to 24 months of age, with male kangaroos sometimes staying with their mothers until three to four years of age.