ANATOMY OF A FEATHER

Written by: Dr. Jacquie Jacob, University of Kentucky

Birds come in different shapes and sizes, but one thing they have in common is feathers. Feathers are unique to birds; that is, everything that has feathers is a bird; that is, everything that has feathers is a bird. Figure 1 shows feathers of various sizes, shapes, colors, and purposes on an adult male rooster.

Rooster with feathers of various sizes, shapes, colors, and purposes
Figure 1. Diagram showing the different feather types on a rooster. Source: University of Illinois. Used with permission.

 

Feathers play three main roles in birds’ lives:

  • Feathers┬áprovide insulation, allowing birds to maintain their body temperatures in a wide variety of environmental conditions.
  • Certain feathers are instrumental in allowing birds to fly.
  • Because they come in different shapes and colors, feathers┬áprovide individual plumage that can serve to camouflage a bird or attract a mate.

The parts of a feather are shown in Figure 2. The shaft runs the length of the feather and is divided into the calamus and the rachis. The calamus is the part of the shaft held in the feather follicle on the skin of the bird. The rachis is the rest of the shaft after the calamus. At the junction of the calamus and rachis is the plumulaceous portion of the vane. The vane is the normal pennaceous portion.

Feather parts
Figure 2. Parts of a flight feather. Created by: Dr. Jacquie Jacob, University of Kentucky

Figure 3 is an electron microscope image of a part of a pheasant secondary flight feather showing the barbs and hooks. Flight feathers must be tough to withstand the rigors of flight. The bards on a flight feather are connected to adjoining bards in the same vane by the hooks on the barbules.

Figure 4 is an electron microscope image of part of a peacock eye feather. This feather is ornamental and not meant to withstand the forces a flight feather must endure. Spacing exists between the barbs, and the hooks do not hold the barbs together. The ridges on the barbs are part of the complex color-producing system present on peafowl.

Electron microscope image of a pheasant secondary flight feather
Figure 3. Electron microscope image of part of pheasant secondary flight feather. Source: John Anderson, The Ohio State University

 

Electron microscope image of part of a peacock eye feather
Figure 4. Electron microscope image of part of a peacock eye feather. Source: John Anderson, The Ohio State University

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