Feathers in Birds- structure & types. PPT
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Feathers in Birds- structure & types. PPT
Feathers in Birds- structure & types. PPT
- 1. Feathers- structure & types Dr Showkat Ahmad Wani
- 2. Introduction • Feathers are unique integumentary derivatives found exclusively in birds. • They serve multiple functions: flight, insulation, camouflage, courtship display, and waterproofing. • Evolutionarily, feathers are believed to have originated from reptilian scales
- 3. Origin and Development of Feathers • Feathers originate from the epidermis, with some contribution from the dermis. • Development begins in feather follicles, which are invaginations of the epidermis into the dermis. • They are keratinized structures, composed of β-keratin, which is lighter and more flexible than α-keratin found in mammals.
- 4. General Structure of a Feather • Calamus (Quill) • The hollow basal part that anchors the feather in the skin. • Fits into the follicle. • Rachis • The shaft extending from the calamus, supports the vane. • Vane (Vexillum) • Composed of barbs extending laterally from the rachis. • Each barb has smaller branches called barbules. • Barbules bear hooklets (barbicels) that interlock, giving the vane its strength and flexibility.
- 5. Microstructure • Barbs Primary branches from → rachis. • Barbules Secondary branches → from barbs. • Barbicels (hooklets) Tiny hooks → on barbules for interlocking. • This structure allows lightweight yet strong architecture essential for flight.
- 6. Types of Feathers (Based on Structure and Function Type Description Function Contour Feathers Large feathers covering the body, wings, and tail. Rachis prominent with interlocking barbs. Shape, color, protection, and flight. Flight Feathers (Remiges & Rectrices) Specialized contour feathers. Remiges on wings; Rectrices on tail. Aid in flight – lift, thrust, steering. Down Feathers (Plumules) Small, fluffy feathers with reduced or absent rachis; barbs do not interlock. Insulation – trap air for warmth. Semiplumes Intermediate between contour and down feathers. Rachis longer than barbs. Provide insulation and smooth body contours. Filoplumes Hair-like feathers with long, slender rachis and few barbs at tip. Sensory – detect feather position and movement. Bristles Stiff, tapering feathers with few/no barbs. Found around mouth, eyes, Protective, sensory in function. )
- 8. Specialized Feathers Powder down feathers: Disintegrate into fine keratin powder used for waterproofing (e.g., in herons). Display feathers: Brightly colored or specially shaped (e.g., peacock tail feathers) used in courtship.
- 10. Molting • The process of shedding and replacement of feathers. • Occurs seasonally or annually. • Ensures maintenance of feather quality for insulation and flight.
- 11. Functions of Feathers • Flight – Aerodynamic design aids in lift and thrust. • Insulation – Down feathers maintain body temperature. • Camouflage – Cryptic coloration helps in predator evasion. • Communication and Courtship – Bright feathers used in mating displays. • Waterproofing – Especially in aquatic birds like ducks.
- 12. Evolutionary Significance • Fossil evidence (e.g., Archaeopteryx) shows feathers predate flight. • Initially evolved possibly for thermoregulation or display. • Later adapted for aerodynamics and flight.
- 13. Thank You