Vertebrate - Structure of Feathers Flashcards
What are the functions of eathers?
Provide insulation
Colour and Form
Enable Flight
How did birds get from scale to feather?
Exaptation
Exaptation
This is a trait originating to solve one problem but is co-opted to solve a new one
What are the stages of feather evolution?
Protrusion of scales from skin forming bumps/ridges for insulation
Proto-feathers for better insulation
More elaboration with branches and barbs
What are the types of feather form?
Contour
Down
Semiplume
Flight Feathers
Contour Feathers
These cover most of the avian body providing insulation from the environment
What is the general struc ture of contour feathers?
Rachies with regularly spaced barbs branched with barbules
What is the rachis made of?
Kertain, being flattened and grooved on the underside to reduce drag in flight
Kertain
This is a naturally occuring strucutral protien found in hair, nails, feathers etc.
What is the surface of the contour covered in?
Preen oil secreted by the preen gland
Preen Gland
This secretes a mixutre of eaxes and lipids applied to the feather for water proof
Down Feathers
These are required for insulation being fine and found under tougher exterior feathers.
What is the structure of down feathers?
Have a shorter rachis with more barbules for softness and insulation, without any barbicles
Why is the calamus at the base important?
Helps in anchoring the feather to the body and nourishing it as it grows.
How do feathers insulate?
Trapping a layer of air, which is a poor heat conductor, to reduce heat loss from body
Semiplume Feathers
These have fluffy vanes with longer rachis and short barbs at the ends, important in insulation and aerodynamics
What is the structure of the semiplume feather?
Intermediate of down and contour, with rachis longer than down but shorter than contour, with denser/more flexibile barbules than contour
What is the branching structure of semiplume?
Branches are more loosely connected, as opposed to rigid and interlocked in contour, and dont contain barbicles
Where are semiplume feathers found?
Beneath contour feathers helping to fill the gap between them