Question

why Penguins do not have air spaces in their bones

Answer 1

A penguin wing is called a flipper. It is a hard, rigid paddle covered with tiny stiff feathers that arenot waterproof (unlike the feathers on the rest of a penguin body). A penguin flipper has a shape comparable to an airplane's wing.

Birds normally have hollow bones, since little weight helps in flying. Due to the shape of their wings, normal birds only gain speed by the down stroke. Penguins however have solid bones, which are heavier. This helps in buoyancy. In addition, penguins gain speed by both the up and down strokes of their flippers. Because a penguin flipper is so hard, it is also used as a weapon in penguin discussions or fights.

Penguins sometimes spread their wings away from their body. This allows them to cool down on a hot day. Heat can flow away from their flippers since this is practically the only part of the body (together with the feet) that doesn't have a thick plumage to conserve heat.

Answer 2

Penguins do not have air spaces in their bones, because it helps to swims in water.