Question

Which of the following is a characteristic feature of the bones of birds?

• A. Four chambered heart
• B. Pneumatic bones
• C. Hollow nerve cord
• D. Large eyes

Answer 1

The correct option is B Pneumatic bones

Pneumatic bones is a characteristic feature of birds.

In biology, the term pneumatic refers to breathing.

Birds have remarkably specialized bones that are pneumatic, because they are full of air sacs that provide a continuous flow of breath throughout their bodies. In short, their lungs are essentially hooked up to their bones.

The bones of birds are lighter in weight than those of mammals. Some of the bones are hollow and actually act as part of the avian respiratory system. These bones, called pneumatic bones, include the skull, humerus, clavicle, keel, pelvic girdle, and lumbar and sacral vertebrae.

Birds have thin, hollow bones to lighten their weight and make it easier for them to fly. They also have a lower number of bones than other animals because the bones have fused together.

The hollow, or pneumatic, bones are filled with air, allowing the bird to defy gravity when it flies. Other aspects of a bird's skeleton also help in flight. For example, the bird has a fused backbone that helps it stay straight while it is in the air. Additionally, a bird's ulna has a series of bumps to which secondary flight feathers attach, providing structural support that permits the bird to catch the air and take off.