Chapter 29, Problem 17A

Summary Introduction

To write:

About the relationship between contour feather and down feather

Introduction:

Birds are different from other vertebrates due to the presence of two characteristics, that is the presence of feathers, and they can fly. Birds belong to class Aves and they are range in size from tiny hummingbirds to large flightless ostriches. Birds are found in forests, deserts, prairies, mountains, and on all seas. The adaptations of birds include they being able to produce their own body heat internally or endothermy, feathers, and light-weight bones.

Explanation of Solution

Feathers that cover the body, tail, and wings of a bird are called contour feathers. Contour feathers consist of a shaft with barbs that branch off. Barbules branch off barbs and are held together by hooks. If two adjoining barbs become separated, they can be rejoined like the teeth of a zipper.

Down feathers are soft feathers located beneath contour feathers. Down feathers do not have hooks to hold barbs together. As a result, the looser structures of down feathers can trap air that acts as insulation.

Conclusion

Contour feathers have hook which helps to holds barbs together. Down feathers do not have hook.