Curious Kids: do penguins fly underwater?

Do penguins fly underwater? - Rhys, age 7, Perth.

Indeed they do. They can’t fly through the air but they can fly underwater.

In other words, a penguin uses the muscles in its chest to bring its special wings, called flippers, downwards. But then it uses the muscles between its shoulders to bring its flippers upwards.

Hummingbirds, which fly in the air, are the only other type of bird that use both the muscles in their chest and between their shoulders to move their wings.

Most birds only use the muscles in their chest. (For the adults in the audience, this is what scientists call a “powered downstroke”. Penguins, and hummingbirds, have a powered upstroke also, whereas other birds have a passive upstroke.)

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A penguin has to work harder than other birds to fly. Even though they work hard, penguins move very fast underwater, especially when they are chasing food such as fish.

They keep streamlined, like a torpedo, with their feet close to their body and under their tail. But a penguin uses its feet, head and sometimes its tail when it wants to change direction.

So if a penguin wants to turn right, its right foot drops down and the penguin turns it head slightly to the right. If the penguin wants to turn left, its left foot comes down and it turns its head slightly to the left. The penguin may move its tail up when it wants to turn in either direction. If a penguin wants to stop, both its feet come down, its tail comes up and the penguin stops flapping its flippers.

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Penguins’ bodies are different to birds that fly in the air in other ways. Birds that fly in air have to be light, so some of their bones have special holes in them, a bit like a piece of Swiss cheese. But penguins don’t have to be light to fly underwater, so their bones are all solid.

Also, the wings of birds that fly in the air can bend. But a penguins’ flippers can’t bend, and this means they can fly strongly through the water without breaking their flippers.

Penguins have adapted to feed in the ocean but to also live on land, where they build nests, lay eggs and raise chicks.

They are truly amazing animals.

If you’re a Curious Kid with a question you’d like an expert to answer, ask an adult to send it to curiouskids@theconversation.edu.au

References

1. ^{^} Curious Kids: if trees are cut down in the city, where will possums live? (theconversation.com)
2. ^{^} Curious Kids: when a snake sheds its skin, why isn’t it colourful? (theconversation.com)