Question

Long hollow bones connected by passages are characteristic of
A. Aves
B. Mammals
C. Reptiles
D. All land vertebrates

Answer 1

Hint: Their light and streamlined body allows them to cut through air. They have forelimbs modified into wings for flying.

Complete Answer:
Vertebrates are the group of animals that possess a backbone or vertebral column. They include birds, fishes, reptiles, mammals etc. Vertebrates also have a well-developed brain, a circulatory system with a heart, mouth with muscles and a pharynx. The vertebrates are further classified into five classes.

Mammals are the animals that give birth to their young and have mammary glands that secrete milk. The bodies of mammals are covered with hair. Reptiles are the animals that have dry scaly skin. They lay eggs.

Aves are the class of vertebrates that are characterised by the presence of feathers and wings. All birds fall under this class. They have long hollow bones that help them to fly. The forelimbs are modified for flight. Its powerful chest muscles help the birds to move their wings during flight. There are internal structures in the bone known as struts or trabeculae that strengthen the bones so that they do not crack in flight. Some bones contain extensions of the air sacs from the lungs. Extensive air sacs enable the bird to get the oxygen it needs to fly quickly and easily.

Thus, the correct answer is option A i.e., Aves.

Note:All birds have wings, but not all birds fly. Most birds have light skeletons with hollow bones. This makes them light enough to fly. Some fused bones, like collarbones or wishbones, make their skeletons stiff relative to mammals. This helps to brace the wings of the birds during the flight.