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Feather - Anatomy & Physiology (view source)
Revision as of 08:58, 14 July 2008
, 08:58, 14 July 2008→Anatomy and Physiology of the Feather
*'''Shaft''': The combination of the rachis and the calamus.
*'''Shaft''': The combination of the rachis and the calamus.
*'''Vane or Vexillum''': The portion of the feather that extends to either side of the rachis and is composed of the barbs and their associated structures. The vane is either '''plumulaceous''' (soft and downy) or '''pennaceous''' (compact and closely knit) depending on the individual type of feather.
*'''Vane or Vexillum''': The portion of the feather that extends to either side of the rachis and is composed of the barbs and their associated structures. The vane is either '''plumulaceous''' (soft and downy) or '''pennaceous''' (compact and closely knit) depending on the individual type of feather.
===Types of Feather===
Feathers are characterised and categorised by the structure of the rachis, barbs and barbules. There are 10 types recognised.
*'''Contour feathers''': these are the predominant feather covering the body.
*'''Coverts''': are small contour feathers of the wing and the tail.
*'''Remiges''': are large stiff feathers of the wing.
*'''Retrices''': are large stiff flight feathers of the tail.
*'''Specialised adapted feathers''': include semiplumes, hypopnea, filiplumes and bristles.
*'''Down feathers''': can be subcategorised into adult, natal and powder down. Powder down are specialised down feathers that disintegrate and produce a powder (keratin) that is spread through the feathers during preening. They are found throughout the body among the down and contour feathers.
===Feather growth===
Feathers arise from feather follicles. These are formes by invaginations of the skin and closely fit the calamus. The feather follicle is analogous with the [[Hair - Anatomy & Physiology#Hair Types|hair follicle]] in mammals. As in mammals, the follicle consists of epidermal and dermal cells and is lined with living and cornified epidermal cells. At the umbilicus of the calamus, the dermis carries a hump of pulp into the tip of the calamus. The follicular wall has an abundant supply of sensory nerve fibres, and the papillae, pulp and feather muscles are also well innervated. Smooth muscles at the base of the feather follicles help maintain body temperature by increasing or decreasing the elevation of the feathers from the skin. [[Skin - Anatomy & Physiology#Beak|Herbst's corpuscles]] at the base of the feather follicles are believed to detect subtle ground vibrations and changes in air current.