Chapter 4 Flashcards

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1
Q

What are the main function of feathers?

A

locomotion, thermoregulation, communication, and protection

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2
Q

Give two basic names of flight feathers

A
  • remiges (wing flight feathers) and Retrices(tail flight feathers)
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3
Q

Name 3 basic structures of flight feathers

A

Rachis, Calamus, and Vane

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4
Q

Calamus

A

proximal, stick like end part of the feather

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5
Q

Rachis

A

shaft of feather

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6
Q

Vane

A
  • feather-like portion of flight feather
  • has (from proximal to distal) a Plumulaceous portion, closed pennaceous portion, and open pennaceous portion
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7
Q

Describe the relationship between, barbs, barbules, and hooklets

A
  • barbs provide a “branch” for proximal barbules on bottom side and hooklets(distal barbules) on top
  • hooklets(distal barbules) connect one to the other to hold the structure seen as a feather(like velcro)
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8
Q

What are the three sets of remiges?

A

primaries(most 9-10), secondaries(varies from 9-25) and tertials( 3-4 usually)

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9
Q

What are contour feathers?

A
  • primary body feathers of a bird
  • has proportion of Plumulaceous barbs and a portion of Pennaceous barbs that are about equal
  • has more plumulaceous barbs than a flight feather
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10
Q

What are afterfeathers?

A
  • the secondary body feathers of a bird
  • it primarily provides insulation
  • forms from same follicle of a typical contour feather
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11
Q

Bristiles

A
  • specialized feathers with both sensory and protective functions
  • often have shaft and aftershaft to collection sensory information
  • just have a straight rachis-like structure
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12
Q

Describe the sequence of development in feathers: epidermis to follicle

A

Feather growth begins with a thickening of the epidermis, the placode, over a condensation of cells in the dermis.
The placode elongates into the tubular feather germ.
Cells proliferate in a ring around the feather germ to create the follicle; production of new keratinocyte cells in the follicle collar push older cells up and out to create the tubular feather.

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13
Q

Describe the follicle development structure in feathers

A
  • The outermost layer becomes the sheath, whereas the inner layer divides into a series of barb ridges that develop into the barbs of the feather
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14
Q

Describe the sequence of development in feathers: follicle collar to fully formed feathers

A

The feather emerges and unfurls from the sheath into its final shape.The follicle collar forms the calamus at the base of the feather.

The branching structure of the rachis and the barbs are created by helical growth of barbs ridges from the ventral to the dorsal side of the follicle:

First, barb ridges fuse to form the rachis, later barb ridges fuse to the rachis. The afterfeather develops by the same mechanism with helical growth toward the ventral side of the follicle.

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15
Q

Which part of the feather follicle makes the feather?

A

The inner layer

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16
Q

What is the Dermal papilla?

A

the structure hump/indent out into the dermis to make the tubular feather germ

17
Q

How many stages are in the hypothesized feather evolution?

A

5 stages

18
Q

Stage I of hypothesized feather evolution

A
  • starts with 1st hollow cylindrical filamentous feather
  • starts with follicle collar structure
19
Q

Stage II of hypothesized feather evolution

A
  • origin of barbs
  • there is differentiation of the follicle collar
  • barbs have formed, a tuft of unbranched barbs attached to the calamus
20
Q

Stage III of hypothesized feather evolution

A
  • 2 possibilities: evolution of barbules or evolution of rachis
  • a feather with barbs and barbules attached at the base to a calamus, includes origin of barbule plates
  • a planar feather with unbranched barbs fused to a central rachis, includes the rachis ridge and origin of helical growth and formation of rachis
  • Leads to planar feather with branched bard and open vane
21
Q

Stage IV of hypothesized feather evolution

A
  • evolution of hooklets
  • we have the closed pennaceous vane (hooklets on one barbule attach to grooves on barbules of adjacent barb)
  • includes differentiation of barbule plates
22
Q

Stage V of hypothesized feather evolution

A
  • we have evolution of a closed asymmmetrical vane (resembling modern flight feathers)
  • includes addition of more barb ridges on one side