Kangaroos are one of the world’s most recognizable marsupials, known for their powerful legs and hopping movement. Like all marsupials, they give birth to their young at an extremely underdeveloped stage. The common name for a baby kangaroo is a joey, a term that applies to the young of many other marsupials as well.
The Specific Term: Joey
The term “joey” describes the young kangaroo from birth until it is fully independent. Born after a gestation period of only about a month, the joey is tiny, typically less than an inch long and weighing under a gram. This newborn is blind, hairless, and lacks fully formed hind legs. Immediately after birth, the joey must use its strong forelimbs and claws to climb unaided through its mother’s fur and into the safety of her pouch.
Early Development in the Pouch
Once inside the pouch, the joey attaches itself to one of the mother’s four teats, which then swells to hold the infant securely in place for its first few months. This marsupial pouch acts as a warm, dark, and protective external incubator where the joey can complete its fetal development. During this time, the joey’s eyes open, its fur grows in, and its limbs strengthen considerably.
Kangaroo mothers can raise multiple joeys at different stages simultaneously. They produce two distinct types of milk tailored to the joey’s needs. The milk for the newborn is high in simple carbohydrates and immunity-rich proteins. The milk for the older, larger joey contains higher fat and protein levels.
Transition to Independence
The joey begins to emerge from the pouch around five to six months old, first poking its head out to observe the world. Short exploratory trips out of the pouch follow, helping the joey strengthen its muscles and learn to graze. The mother’s pouch remains a safe haven, and the joey will quickly dive back in headfirst if it senses danger or feels cold.
Depending on the species, the joey usually makes its permanent exit from the pouch between eight and ten months of age. Even after leaving the pouch, the young kangaroo remains dependent on its mother for nourishment. It continues to nurse for several more months, often until it is over a year old, before being fully weaned and achieving true independence.