Page 71 - Design in Nature

Flawless Flying Machines: Birds 69

DESIGN IN BIRD EGGS
The miraculous creation of birds does not end with wings, feathers or
their migration skills. Another extraordinary design feature of these

creatures is in their eggs.
However ordinary it may seem to us, the egg of a chicken has about
fifteen thousand pores resembling dimples on a golf ball. The spongy
structure of smaller eggs can only be observed under the microscope. These

spongy structures give eggs added flexibility and increase their resistance to
impact.
An egg is a miracle of packaging. It
supplies all the nutrients and water that the

developing foetus needs. The yolk of the
egg stores protein, fats, vitamins and
minerals, and the white works as a
reservoir of fluid.

The developing chick needs to
inhale oxygen and exhale carbon
dioxide. It also requires a source of
heat, calcium for its bone

development, protection of its fluids,
protection against bacteria and
physical impact. The eggshell provides
all of these for the chick, which breathes

through a membranous sac that develops in the
embryo. Blood vessels in this sac bring oxygen to the
embryo and take carbon dioxide away.
Eggshells are amazingly thin and sturdy, and so transmit the body heat

of the brooding parent.