Look at a bird feather close up sometime. It is really an amazing part of a bird's anatomy, made to serve many functions. The image shown at right in Figure 1 is that of a contour feather, the largest of the feathers you'll find on a bird. It is labeled with its basic parts to help you understand how complex it really is.
Calamus:
Commonly called the quill, it is the smooth, non-colored part of the feather shaft, which extends under the skin.
Rachis:
The portion of the central shaft that rises above the skin. It is the base from which the barbs extend.
Vane:
The part of the feather that has barbs.
Barbs:
Set of fibers, which come off the rachis at a 45-degree angle (see Figure 2).
Barbules:
Very small fibers found on the barb. Barbules from one barb cross those of the next at a 90-degree angle (see Figure 2).
Hooklets:
Barbules have these, to hook the barbules together, like a zipper, forming a tight, smooth surface.
Afterfeather:
Some feathers have a small growth at the base of the vane, which have barbs but no hooks.
