A fossil penguin named Kumimanu biceae stood about 1.65 meters tall and weighed about 100 kilograms. The Kumimanu fossil is about 55 to 60 million years old, close in age to the oldest known penguins; early penguins lived in warm seas, so penguins did not begin in the cold. The emperor penguin is the biggest penguin; a grown emperor penguin stands about 1.1 meters (45 inches) tall. A big emperor penguin can weigh about 40 kilograms (88 pounds); the king penguin is the second largest penguin. An adult king penguin stands 85 to 95 centimeters tall; the little penguin is the smallest kind of penguin. Penguins as big as or bigger than emperors lived between about 50 and 20 million years ago.
The giant penguins vanished from the fossil record about 20 million years ago; one idea blames the rise of seals and toothed whales. Leopard seals and killer whales hunt penguins in the water; only two kinds of penguin, the emperor and the Adelie, are true residents of the Antarctic continent. Adelie penguins are hunted mostly by leopard seals, and skuas take their eggs and chicks. Emperor penguins can swim up to 20 kilometers an hour, and Adelie penguins swim 4 to 8 kilometers an hour; an emperor penguin can dive more than 500 meters deep. The longest emperor penguin dive on record lasted 22 minutes; penguins swim by pushing themselves along with their flippers. Penguins have black on their backs and white on their bellies; the black and white coloring is called countershading and makes a penguin hard to see in the water.
Emperor penguins breed in the middle of the Antarctic winter; a father emperor penguin stands with the egg for about 65 days. While he holds the egg, the father emperor eats nothing and loses about 40 percent of his body weight. Emperor penguins build up fat before winter and live on it while they fast during breeding; many penguins return to the same mate and the same nest site year after year. Penguins lay only one or two eggs at a time; penguin chicks gather in groups called crèches while their parents go to find food. Penguin parents bring up food from their stomachs to feed their chicks; emperor penguins can live 20 years or more.
As of November 2026, emperor penguins are officially listed as at risk of extinction: threatened under the United States Endangered Species Act and Endangered on the IUCN Red List. As of November 2026, the main reason is shrinking sea ice, which is expected to keep shrinking for decades. As of November 2026, about two-thirds of the 18 penguin species are listed as threatened by the IUCN. As of November 2026, the gentoo penguin population is thought to be stable overall, although some colonies grow and others shrink. As of November 2026, African penguins are critically endangered, and their numbers have been falling since the early 1900s. Penguins are indicators of the health of the ocean and of climate change; at least one emperor penguin colony has all but disappeared as the sea ice changed.
Words to know
- fossil: old remains
- vanished: went away
- flippers: limbs for swimming
- nest: egg home
- Endangered: nearly gone
