Feathers-of-Birds

Feathers of Birds: Structure, Types, & Functions of Feathers

Feathers of Birds

Feathers are the ultimate characteristic of birds. No other (living) animals have them.

  • The qualifier is required because feathers have now been found in fossil imprints of some dinosaurs and related reptiles.
  • Like the hair on mammals and scales on reptiles, feathers belong to the integument (skin).
  • All are mainly made up of keratin, which is also the main ingredient of human nails, animal claws, and the scales on the legs and feet of birds.
  • Feathers are impressive structures, both extremely strong and very light.
  • They undergo long flights and are bent and twisted, yet they are hardly ever harmed.
Structure of a Common Feather

To comprehend the structure of a feather, a contour feather which happens on the basic body, wing, and tail, can be considered typical. A typical contour feather consists of a central axis, primary stem or scapus, and an expanded distal portion, the vexillum or vane.

  1. Scapus (Axis): The scapus is divided into a basal portion, the calamus, and an upper shaft or rachis.

❖ Calamus: The calamus is hollow, tubular, and semitransparent. The base of the calamus remains inserted into a pit or hair follicle of the skin. The calamus opens below by a small opening called the inferior umbilicus, which gets a little, conical, nutritious dermal papilla from the dermis. Another pore called the remarkable umbilicus, happens on the forward side of the junction of the calamus and rachis.

❖ Rachis: The part of the scapus above the calamus is a rachis. It forms the longitudinal axis of the vane. It is solid, opaque, roughly quadrangular in transverse section, and filled with a closely packed mass of pith cells.

  1. Vane:

❖ The rachis bears a fan-like, webbed, or expanded membranous part of the feather, the vexillum or vane. The vane is divided by rachis into two unequal lateral halves. Its proximal end is wider than the distal end. Each half of the vane is composed of a series of numerous (about 600), parallel, closely spaced, fragile, lateral, thread-like structures called the barbs or rami. The barbs occur obliquely outwards from the two lateral sides of the rachis.

❖ Plumes are always shed or moulted at regular intervals, as a rule yearly after the breeding season.

Types of Feathers

Feathers come in many different shapes, but all of them can be classified into 6 different types of feathers. The plumes we are utilized to seeing are flight and contour. Down feathers are what we use in pillows, quilts, and coats. The other 3 feathers, semi plume, filoplume, and bristle, are not as typical, however still helpful to birds.

Types-of-Feathers

Flight feathers

Flight feathers are present in two places on birds: the wings and tail. Flight feathers are long, and on the wings, one side of the vane broader than the other. They also have more powerful barbules which give them more strength for flight.

Contour feathers

Contour feathers offer shape and color to the bird. They are found everywhere except the beak, legs, and feet. Contour feathers are colored just at the ends (the only part that we see). At its base, a contour feather becomes downy which assists in insulating the bird.

Semiplume plumes

Semiplume feathers are a cross between down and contour feathers. Unlike down, they do have a well-formed shaft. However, they do not have well-developed barbicels that make them soft. Semiplume feathers are present below contour feathers and are used for insulation.

Down feathers

Down feathers have little or no shaft. They are soft and fluffy. Down feathers help insulate birds by trapping air. Some birds, such as herons, have unique down feathers called powder down which breaks up into a great powder. The bird then spreads this fine powder all over its body to act as a water repellent.

Further Reading:  SDS – PAGE [Principle, Working, Uses of SDS – PAGE]
Filoplume feathers

Filoplume feathers are extremely small. They have a tuft of barbs at the end of the shaft. Unlike other feathers which are attached to muscle for motion, filoplume feathers are connected to nerve endings. These feathers send out messages to the brain that provide information about the positioning of feathers for flight, insulation, and preening.

Bristle feathers

Bristle feathers are stiff with only a few barbs present at the base. Bristle plumes are found around the mouth of insect-consuming birds where they function as a funnel. They can also be found around the eyes where they work like eyelashes.

Functions of Feathers

They serve a varied selection of functions which have been summed up listed below:

  1. Protection:

Plumes form a lightweight, invulnerable, flexible, resilient, and water-resistant body covering. They protect the underlying tender skin from all types of mechanical, chemical, pathological, and ecological injuries.

  1. Heat Retention:

The birds have a consistent body temperature level which frequently remains between 104 ° and 112 ° F, even in subzero weather conditions. Thus, the plumes serve the most essential function of retention of heat since the plumage forms an effective, non-conducting covering with its innumerable dead air spaces, useful as insulation.

❖ In winter the heat loss is lowered to a minimum by fluffing out the feathers, which increases the depth of insulating material by contributing to the air spaces within the feathery layers.

❖ In warm weather, the feathers are frequently held near the body to enable some escape of body heat.

  1. Camouflaging (Protective Coloration):

The feathers of various birds have rather characteristic protective coloration like the pigmentation of their surroundings, that make them indistinguishable from their regular environments and, thus, serve to safeguard them from their opponents.

Camouflaging

  1. Sexual Dimorphism:

Feathers provide protective pigmentation and also sexual display. Sexual dimorphism is common in monogamous in addition to polygamous species. Colors and erectile plumes end up being indication stimuli that evoke or launch particular reactions and entire pattern of behavior in competitors and mates.

For example, on many birds, the crown plumes are modified into crests (peacock), and decorative plumes (California quail).

Sexual-Dimorphism

MCQs (Multiple Choice Questions) – Feathers of Birds

  1. What is the main component of feathers?
    • A) Collagen
    • B) Keratin
    • C) Elastin
    • D) Melanin
    • Answer: B) Keratin
  2. Which part of the feather is hollow and tubular, remaining inserted into the skin?
    • A) Vane
    • B) Rachis
    • C) Calamus
    • D) Barb
    • Answer: C) Calamus
  3. How many types of feathers are typically classified in birds?
    • A) 3
    • B) 4
    • C) 5
    • D) 6
    • Answer: D) 6
  4. Which feather type is characterized by having well-developed barbicels and is used for insulation?
    • A) Semiplume feathers
    • B) Contour feathers
    • C) Down feathers
    • D) Filoplume feathers
    • Answer: C) Down feathers
  5. Where are bristle feathers commonly found on a bird?
    • A) Wings
    • B) Tail
    • C) Around the eyes
    • D) Below contour feathers
    • Answer: C) Around the eyes
  6. Which function do feathers primarily serve for birds in terms of temperature regulation?
    • A) Conducting heat
    • B) Insulation
    • C) Evaporative cooling
    • D) Reflecting sunlight
    • Answer: B) Insulation
  7. What type of feathers are present on the body, wings, and tail of a bird?
    • A) Semiplume feathers
    • B) Filoplume feathers
    • C) Contour feathers
    • D) Down feathers
    • Answer: C) Contour feathers
  8. What is the primary purpose of down feathers in birds?
    • A) Flight
    • B) Camouflaging
    • C) Insulation
    • D) Sexual display
    • Answer: C) Insulation
  9. Which part of a feather is responsible for sending messages to the brain about feather positioning?
    • A) Rachis
    • B) Calamus
    • C) Vane
    • D) Filoplume feathers
    • Answer: D) Filoplume feathers
  10. What is the function of bristle feathers around the mouth of insect-eating birds?
    • A) Flight
    • B) Insulation
    • C) Camouflaging
    • D) Funneling insects
    • Answer: D) Funneling insects
  11. What is the primary purpose of fluffing out feathers in winter?
    • A) Aesthetic display
    • B) Heat retention
    • C) Camouflaging
    • D) Enhancing flight
    • Answer: B) Heat retention
  12. What type of feather serves as a cross between down and contour feathers?
    • A) Semiplume feathers
    • B) Filoplume feathers
    • C) Bristle feathers
    • D) Contour feathers
    • Answer: A) Semiplume feathers
  13. Which feather type has little or no shaft and is used in making pillows, quilts, and coats?
    • A) Contour feathers
    • B) Filoplume feathers
    • C) Down feathers
    • D) Bristle feathers
    • Answer: C) Down feathers
  14. What is the primary function of feathers related to sexual dimorphism?
    • A) Heat retention
    • B) Camouflaging
    • C) Flight
    • D) Sexual display**
    • Answer: D) Sexual display
  15. What is the coloration of feathers that makes birds indistinguishable from their surroundings?
    • A) Melanin
    • B) Carotenoids
    • C) Anthocyanins
    • D) Protective coloration
    • Answer: D) Protective coloration
  16. Which part of the feather is solid, opaque, and forms the longitudinal axis of the vane?
    • A) Rachis
    • B) Calamus
    • C) Barb
    • D) Vexillum
    • Answer: A) Rachis
  17. How many types of lateral thread-like structures (barbs or rami) are found on each half of the vane?
    • A) Approximately 100
    • B) Approximately 200
    • C) Approximately 400
    • D) Approximately 600
    • Answer: D) Approximately 600
Further Reading:  Comparison of Rhizome and Root

 

FAQs (Frequently Asked Questions)

  1. Q: Are feathers exclusive to birds?
    • A: Yes, feathers are a distinctive characteristic of birds. However, they have also been discovered in fossil imprints of some dinosaurs and related reptiles.
  2. Q: What is the primary component of feathers?
    • A: Feathers are primarily composed of keratin, which is also found in human nails, animal claws, and the scales on the legs and feet of birds.
  3. Q: How do feathers manage to stay strong and light despite the challenges of long flights?
    • A: Feathers are both extremely strong and very light, allowing them to endure the bending and twisting experienced during long flights. This is due to their impressive structure and composition.
  4. Q: What are the main parts of a common feather?
    • A: A common feather consists of the scapus (axis), which includes the basal calamus and the upper rachis. The distal portion, the vexillum or vane, is an expanded membranous part.
  5. Q: What is the function of the calamus in a feather?
    • A: The calamus is the hollow, tubular base of the scapus, remaining inserted into the skin. It opens below through a small opening called the inferior umbilicus.
  6. Q: How many types of feathers are there, and can you name them?
    • A: There are six types of feathers: Flight feathers, Contour feathers, Semiplume feathers, Down feathers, Filoplume feathers, and Bristle feathers.
  7. Q: What is the function of contour feathers?
    • A: Contour feathers provide shape and color to the bird. They are found everywhere except the beak, legs, and feet. Contour feathers also have a downy base for insulation.
  8. Q: What distinguishes flight feathers from other types?
    • A: Flight feathers are long and have one side of the vane broader than the other. They also have stronger barbules to provide more strength for flight.
  9. Q: How do down feathers contribute to insulation in birds?
    • A: Down feathers have little or no shaft, creating a soft and fluffy structure that traps air. This trapped air helps insulate birds. Some birds, like herons, have special powder down for water repellency.
  10. Q: What is the function of filoplume feathers, and how are they connected to the nervous system?
    • A: Filoplume feathers are small and have a tuft of barbs at the end of the shaft. They are connected to nerve endings, providing information to the brain about feather positioning for flight, insulation, and preening.
  11. Q: How do feathers contribute to the protection of birds?
    • A: Feathers form a lightweight, invulnerable, flexible, resilient, and water-resistant body covering. They protect the skin from various types of injuries.
  12. Q: How do feathers assist in heat retention for birds?
    • A: Feathers help birds maintain a constant body temperature by forming an effective, non-conducting covering with numerous dead air spaces, acting as insulation.
  13. Q: Why do birds fluff out their feathers in winter?
    • A: Fluffing out feathers in winter increases the depth of insulating material by contributing to the air spaces within the feathery layers, reducing heat loss to a minimum.
  14. Q: What is the purpose of protective coloration in feathers?
    • A: The protective coloration in feathers makes birds indistinguishable from their surroundings, serving as camouflage and protecting them from predators.
  15. Q: How do feathers contribute to sexual dimorphism in birds?
    • A: Feathers provide protective pigmentation and serve as indicators for sexual display. Different colors and erectile plumes become stimuli for specific reactions and behaviors in competitions and mating.
Further Reading:  Digestive System of Birds - MCQs + FAQs

 

Summary: Feathers of Birds

The tutorial explores the intricate world of bird feathers, highlighting their unique characteristics, structural components, diverse types, and multifaceted functions. Emphasizing their exclusivity to birds, the tutorial acknowledges fossil evidence of feathers in certain dinosaurs and related reptiles. Composed mainly of keratin, the same material found in human nails and animal claws, feathers exhibit a remarkable combination of strength and lightness, enabling them to endure the challenges of long flights.

The structure of a common feather is dissected, detailing the scapus, calamus, rachis, and vane components. The six main types of feathers – flight, contour, semiplume, down, filoplume, and bristle – are presented, each serving distinct purposes. Flight feathers, located on wings and tail, boast strength for flight, while contour feathers provide shape and color to the bird’s body. The tutorial delves into the unique characteristics of semiplume, down, filoplume, and bristle feathers, elucidating their roles in insulation, air trapping, nerve signaling, and specialized functions around the eyes and mouth.

Functions of feathers are extensive, encompassing protection from various injuries, heat retention for temperature regulation, and camouflage through protective coloration. The tutorial highlights the sophisticated mechanism of heat loss reduction in winter and the strategic holding of feathers in warm weather. Additionally, feathers play a crucial role in sexual dimorphism, serving as indicators in both monogamous and polygamous species, evoking specific behaviors in competitions and mating rituals.

In summary, the tutorial provides a comprehensive understanding of bird feathers, celebrating their uniqueness, structural complexity, and the diverse functions that contribute to the survival and adaptation of avian species.