by Mayy Feras

Created on: January 29, 2009

A feather is the epidermal growth that makes up a birds coat, or plumage. They help birds to fly, provide insulation, waterproof the birds skin, and make up the birds coat. Like hair, feathers only grow from certain designated parts of a bird's body, tiny follicles in the epidermis of birds that produces keratin, the same substance that fingernails are made of. The keratins in feathers- which are also found in beaks, claws - and the claws and scales of other animals - are composed of hydrogen bonded protien strands. These protein strands are intertwined into structures that are stronger than the keratin found in the hair and hoofs of mammals.

There are two basic types of feathers: Vaned feathers and down feathers.

Pennaceous feathers (also known as contour feathers) are vaned feathers that have a central shaft (also known as rachis) with vanes branching off to either side. These vanes are commonly known as barbs, because they have tiny barbules that connect with one another, forming a microscopic "net". This net helps to keep dirt and excessive moisture away from the bird's skin.Pennaceous feathers are commonly known as the "outer feathers", providing a barrier between the softer, more delicate feathers underneath.

The down feathers of birds create a fine, soft layer beneath the tougher, exterior feathers. It provides a thermal insulation for birds (and is now used to stuff pillows, jackets, blanket etc.) Baby birds of some species have a special kind of natural down (neossoptiles) that grow out when the normal feathers (teleoptiles) emerge.

Feathers also aid in the distinctive coloration of many birds.

The main parts of the feather are the vane, rachis, barb, after feather, hollow shaft, and calamus.

Flight feathers are the long, asymmetrically shaped feathers on the wings or tail of a bird. The ones that appear on the wings are called remiges. Tiny serrations on the leading edge of their remiges help birds of prey to fly silently.

Remiges are located on the posterior side of the wing. The most important of the remiges are the primary feathers.

Primaries are connected to the manus (the "hand"); these are the longest and narrowest of the remiges (particularly those attached to the phalanges), and they can be individually rotated. These feathers are especially important for flapping during flight, as they are the main source of thrust, moving the bird forward through the air.

The secondary feathers remain close together in flight (they do not move separately like primaries) and help to provide lift by creating the overall shape of the bird's wing.

Tertial feathers act as a protective cover for all or part of the folded primary and secondary feathers.

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