Question

penguins do not have air spaces in their bones give reason

Answer 1

Penguins do not have air spaces in their bones because they do not need to fly. Air spaces are present in the bones of the wings of birds that can fly to decrease their weight

Answer 2

Unlike other birds, penguins do not have hollow bones. Their bones are comparatively heavy, filled and solid which helps penguin to swim under water rather then fly in the air.

Studies show that this is an evolutionary drift because not all flightless birds have heavy bones. Heavy bones in penguin help them swim in water and stay under water.