Julia Glenn, of Ilam Primary School, asks :-

Why can't penguins fly?

John Darby, a zoologist at the Otago Museum, responded.

Of the 8,500 bird species only about 390 of these swim in water.

As a scientist who works with penguins I feel that penguins do fly - but they do so under water and are easily the best adapted of those which do.

Perhaps the best way to consider whether birds swim or fly under water is to decide if the bird uses its wings or its feet to propel itself. For example, ducks and shags use their feet to paddle on top of the water and also to swim under water. But penguins and a few other seabirds use only their wings. The feet and tail are used only for steering.

A swimming bird must have short, waterproofed feathers. (Imagine a sparrow trying to swim. Its feathers would very quickly get wet and become very tangled.) To fly underwater a bird must also be very streamlined. Short feathers help this and those on the wings (flippers) must be very short. So if you look at penguins they are streamlined, have short, waterproofed feathers on the body and very short feathers on the flippers (wings).

Penguins are most remarkable fliers underwater. At times they can reach speeds of up to 22 kilometres per hour. Each day a yellow-eyed penguin, for instance, will regularly swim up to 25km and dive up to one hundred times to a depth of at least 140 metres.

The largest penguin, the Emperor, has been known to dive to 385 metres and stay underwater for up to 18 minutes.

I find Penguins absolutely fascinating.