Animals are born anywhere from helpless to nearly self-sufficient, and scientists place them on a spectrum. Giraffes are at the self-sufficient end. They are precocial, which means they are born ready to move. A newborn giraffe's nervous system is ready at birth, like that of a one-year-old human child ready to walk. A foal, which is a baby horse, stands within about 55 minutes and walks or runs within about 90. Its mother's first milk, called colostrum, is full of antibodies that protect it from disease, but the foal absorbs them much worse after 12 hours, which is why it must nurse early.

The giant panda sits near the other end of the spectrum. A newborn is pink and blind, and it weighs only about 1/900th as much as its mother. Its pink skin is covered with white fur within about 48 hours, the black markings come next, and the fur is all filled in by about three weeks. Its mother feeds it up to 14 times a day in its first weeks, and the cub gains weight fast. Giant pandas are born smaller, compared with their mothers, than nearly any other mammal except marsupials, and as of November 2026, scientists still do not know exactly why.

Black bear cubs are among the smallest newborns of any placental mammal compared with adult size. A newborn weighs less than a pound and is born naked and blind, in the den in the middle of winter, while its mother is asleep there. The cubs drink her milk all winter, and by spring they weigh about 5 to 7 pounds.

Wolf pups are born blind and deaf, and they weigh about a pound. A wolf pup's eyes open at about two weeks old, although at first it can only crawl. Sled dog puppies are born with their eyes and ears closed and cannot make their own body heat. They rely on their mother and littermates to stay warm.

A newborn kangaroo is only about the size of a jellybean, and it crawls into its mother's pouch by itself, using its front legs. There it latches onto a teat inside the pouch, and the teat swells and holds it in place for about three and a half to four months. A marsupial mother's pouch is a safe place where her young finish developing, and a joey spends its first six months relying on the pouch for protection and milk. Then it comes out to learn how to forage and avoid predators, although it keeps drinking its mother's milk until it is about 10 to 12 months old.

Emperor penguins start their nesting in the dead of winter. Incubating an egg takes around four months, so the chick hatches when there is the most food in the ocean nearby. The dad keeps the egg warm on top of his feet, tucked under a fold of belly skin, while the moms go to sea to feed on fish, and the chick then stays on a parent's feet under a warm flap of belly skin for the first weeks. In a 48-hour blizzard the whole huddle can drift as much as 200 meters downwind, and the dads take turns moving from the cold edge to the warm middle.

A mother sea turtle comes ashore at night, digs a nest in the sand, lays her eggs, covers them and goes back to the sea, and she does not stay to care for her eggs. Sea turtles come out of the nest together. When the first hatchling breaks free and digs, the movement sends vibrations through the nest, and the other hatchlings begin to dig out too. Hatchlings find the sea by the slope of the beach and by the moon or starlight on the water. Only about one in 1,000 to one in 10,000 sea turtle hatchlings is estimated to survive to adulthood.

In the 1930s, Konrad Lorenz showed that birds hatched in an incubator, with no parents around, follow whatever they first see. He got a one-day-old duckling and found that it followed him as if he were its parent. He called this early following response imprinting. Orangutan babies, by contrast, cling to their mothers as the mothers move through the trees. The mothers teach them which foods to eat, where to find them, in which trees and in which seasons. They are weaned at about age six or seven, and a Sumatran orangutan mother may wait at least eight years before she has her next baby.

A tadpole's tail is not shed. The body slowly absorbs it and uses it as a source of energy. Tadpoles in ponds that are drying up can speed up their change into frogs, or they can delay it, and some frog species skip the swimming tadpole stage and develop into small frogs inside the egg. A single frog can lay up to 20,000 eggs at once, but only a small percentage survive to adulthood. Bullfrog tadpoles may take several years to turn into frogs. Frogs are indicators of ecosystem health: changes in the timing or success of any life stage can signal wider environmental pressures.

Words to know

• precocial: ready at birth
• colostrum: first milk
• imprinting: early following
• spectrum: range
• weaned: off mother's milk