Page 235 - The Evolution Deceit

The Extraordinary Structure of the Bird Feathers

On first examination, bird feathers don’t appear to contain that many features. When
inspected more carefully, however, feathers— which are light but strong and imper-
meable to water—are seen to have a highly complex structure.
In order to be able to fly, birds must weigh as little as possible. In line with that re-
quirement, feathers consist of keratin proteins. On both sides of each shaft of the
feather are some 400 side branches, or barbs, each with approximately 800 tiny
hooks, or barbules. On each of these 800 bar-
bules are 20 smaller hooked filaments, called
barbicels, that hold the parallel barbules to-
gether, like zippers connecting two pieces
of cloth. There are approximately 300
million hooks in any single feather;
and the total number of hooks in all
the feathers on any one bird is
approximately 700 billion.
The complex structure of
barbs and hooks that
lock a feather together
serves a most impor-
tant function. Feathers
need to be closely
bound together in
order not to become
separated, frayed
and useless when
the bird flies.
Thanks to this
mechanism, each
feather is bound
together so
closely that nei-
ther strong
winds nor rain
can break up its
continuous sur-
face.
The down-feathers
are not the same as
those on the wings and tail.
The very large tail feathers
serve as rudders and brakes.
Meanwhile, the wing
feathers increase surface
area and thus, lift by open-
ing up when the wing flaps
down.