Chapter 29, Problem 18A

Summary Introduction

To write:

About the relationship between preen gland and contour 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. Birds repair broken links when they preen their feathers. They use their bills to preen their feathers, drawing the length of the feather through the bill to zip up broken links.

Many birds have a preen gland, a gland located near the base of the tail that secretes oil. During preening, birds spreads oil from the preen gland over the feathers, thereby adding a waterproofing coating.

Conclusion

Contour feathers have hook which helps to holds barbs together. Preen glands provide waterproof coating over the feathers.