Are Penguins Mammals?

Written by Krishna Maxwell
Updated: September 20, 2022
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Key Points

  • Penguins are not mammals, rather, they are flightless birds.
  • It may look like penguins have soft, short fur, but they actually have feathers.
  • Male penguins produce a substance called crop milk that they feed to their babies. However, it is not milk at all.

Penguins, or Sphenisciformes, are not mammals, but birds. They are different from mammals in that they have feathers instead of hair or fur, and unlike most mammals penguins lay eggs instead of giving live birth. Like all modern birds, penguins don’t have teeth, though most mammals do. They also don’t feed their babies with milk exactly the way mammals do, but more about that later.

Penguins are, like other birds, a type of therapod dinosaur that survived the extinction of other dinosaurs such as Tyrannosaurus Rex. Birds are much younger than mammals as a Class, having appeared on earth around 60 to 70 million years ago compared to mammals’ appearance 210 to 300 million years ago.

Unlike mammals, penguins lay eggs rather than giving live birth.


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Why Do People Think Penguins Are Mammals?

People might mistake penguins for mammals because they really don’t look like any other type of bird. Auks look somewhat like them, but auks can fly. Sphenisciformes are bipedal, and they have given up the power of flight. Their wings have developed into flippers that help them swim, which they do as gracefully as other birds fly. They are warm-blooded, and smooth, dense plumage sometimes looks more like sleek fur than feathers. Their chicks often look like they’re wearing dust-colored fur coats, but they are covered with down. The black and white coloration of their plumage may also make people think of a mammal such as a honey badger, a skunk, or even a killer whale.

Emperor penguin fathers do feed their chicks with crop milk when they’re first hatched. This is a substance that resembles cottage cheese and is made of proteins and fats. It’s not regurgitated fish but a nutrient the bird actually produces from a gland in its throat. This still doesn’t make a penguin a mammal.

Only three bird species are known to produce crop milk, and they are the male emperor penguin, the pigeon, and the flamingo. Second, only the father emperor penguin produces it. Mammalian milk is produced exclusively by the mother’s mammary glands.

Another thing that might make people think Sphenisciformes are mammals is that they take great care of their young. Emperor penguins are famous for the extremity of their devotion. The male stands around in subzero temperatures for weeks incubating the egg then keeping the chick from freezing in his brood pouch. He does this until the mother returns from the sea, where she has been feeding. He then surrenders the chick to the mother and goes to the sea himself to feed, as he has not eaten the whole time and is half-starved. He no longer produces crop milk, but he and the mother take turns feeding the chick regurgitated fish and krill. They do this for five months.

Penguins, like many birds, are devoted parents who work together to raise their young. We humans tend to think of this as a human trait, but many species of birds share this behavior. Like humans, the babies of birds are very helpless and require extensive care until they grow enough to survive on their own. Penguins often live in very harsh climates so good parenting is a must if the babies are to survive.

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The photo featured at the top of this post is ©

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About the Author

Krishna is a lifelong animal owner and advocate. She owns and operates a small farm in upstate New York which she shares with three dogs, four donkeys, one mule, and a cat. She holds a Bachelors in Agricultural Technology and has extensive experience in animal health and welfare. When not working with her own animals and tending her farm, Krishna is helping other animal owners with behavior or management issues and teaching neighboring farmers about Regenerative Agriculture practices.

FAQs (Frequently Asked Questions) 

Are penguins endangered?

As with nearly all kinds of animals, some species of sphenisciformes are endangered. Indeed, the population of most species is in decline, save the king penguin. Some endangered penguins include:

Northern rockhopper. This bird, with its interesting gold tasseled crest, is listed as endangered. Its found in the Indian and the southern Atlantic Oceans.

• Snares. This New Zealand bird is considered vulnerable.

African. The conservation status of this bird is endangered.

Magellanic. Found in southern South America, this penguin is near threatened.

Galapagos. This bird, the only penguin that lives north of the equator, is endangered.

How many species are there?

Scientists believe there are between 17 and 20 types of penguins in the world that belong to six genera. All belong to the Spheniscinae subfamily. The three-foot-seven-inch tall emperor is the largest, while the fairy penguin, which stands just over a foot in height, is the smallest. But the Emperor isn’t the biggest penguin that ever lived. That was probably Anthropornis nordenskjoldi, an extinct creature that lived between Antarctica and New Zealand and could have been around six feet tall.

Where are penguins found?

The great majority of sphenisciformes are found south of the equator. There is only one species of penguin that’s found north of the equator, and it is barely north at that. It is the Galapagos penguin, and it is found in the Galapagos Islands, which belong to Ecuador. But even though sphenisciformes are found south of the equator, not all of them live in such brutally cold places as Antarctica. Some are found in South Africa, New Zealand, Australia, and Argentina. Penguins like waters that are cold and nutrient-rich but strangely, none are found in the Arctic regions.

Are penguins edible?

They are edible, but they don’t make the best eating, as the early explorers of the South Pole discovered. The crews ate penguin meat and eggs when they ran low on other food. The meat is described as fishy and oily. The eggs had a more palatable fishy taste, and the whites never congealed even if they were cooked. Now, it is illegal to eat penguins or their eggs in most places.

Are penguins omnivores, herbivores or carnivores?

They are carnivores. They eat fish, squid, amphipods, krill and other types of marine life that they catch as they swim underwater. Not only this, but they can drink salt water. They excrete the extra salt through their noses and guano.

Are penguins dangerous?

They are not dangerous, but they have very little fear of humans or anything else since most healthy adults have no natural predators when they are on land. This is true even of little birds. Indeed, the diminutive Adelie penguins have been seen chasing off skuas, large, aggressive seabirds that prey on chicks and eggs.

Do penguins migrate?

These birds do migrate, but they obviously don’t migrate like other birds. They must swim, walk, hop or toboggan when they migrate, and the trip can be grueling, especially for the very young and the very old. Sphenisciformes migrate for the same reasons as other birds, such as the seasonal availability of food, for breeding or because the ice threatens to become impassable and the weather has become too cold even for their comfort. Adelies, which live in Antarctica’s Ross Sea area, migrate about 8100 miles from their nesting sites to their feeding grounds and back. The more south the birds live, the more likely they are to travel north.

How fast do penguins swim?

Penguins can swim in the water nearly as fast as other birds fly in the air. The gentoo, which is found in Antarctica and the Falkland Islands, has been clocked at 22 miles per hour in the water.

Are they monogamous?

Penguins are monogamous but only for one breeding season. Yet, during that season they will bond faithfully to one mate. They may or may not choose the same mate when the next breeding season arrives though some penguins do mate for life.

How do penguins keep warm?

These doughty birds are warm-blooded, and they have evolved the ability to shunt their blood around their bodies to make sure that they don’t freeze even in the coldest weather. They also have specialized feathers that trap heat, especially when they’re underwater. A well-fed penguin also has a lot of fat, and they sometimes huddle together by the thousands to keep warm. The emperor, being a large bird, is able to conserve its body heat better than other penguins. Indeed, Antarctic penguins need it to be a bit chilly, for heat stresses them. This is why global warming is such a threat to them.

How long do penguins live?

The lifespan of a penguin depends on its species. Magellanics can live as long as 30 years, gentoos can live about 13 years, fairy penguins about six years and emperors 15 to 34 years, though they can live for 50 years in captivity.

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