Thursday, 6 October 2016

Feather facts

Feathers appear to have evolved from scales and are composed of B-keratin. Scales and feathers develop in a similar fashion. In actuality, birds have both feathers and scales. You can find scales on the legs and feet of most birds.

Feathers are incredibly strong and yet are incredibly flexible. To allow both lift and forward movement, feathers can bend at almost a right angles.

Feathers are made of a shaft, called the rachis and the vanes on either side. Vanes are made of barbs that are arranged side by side up the shaft of the feather. Barbules grow from the barbs, which have tiny hooks that interlock in a similar way to hook-and-loop fasteners. The short bare part at the base of the shaft is called the calamus. If viewed crossways, the calamus is basically hollow.

There is an opening at the very tip of the base where the blood supply entered the feather when it was growing. Once a feather is fully grown, the supply of blood is sealed off and the feather itself becomes “dead,” similar to the ends of human nails.

On most flight feathers, the vanes are of unequal length. This gives feathers the ability to twist under air pressure. The large flight feathers are attached to bone by connective tissue, and have little or no down at the base. All other feathers are attached to muscles below the skin.

Source: Raptor Research Foundation

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