Page 74 - Design in Nature

High Low

Shell
Oxygen
Water
Carbon
dioxide Pore canal

Low High Shell
membranes
CONCENTRATION
LEVELS AND
Chorioallantois
DIRECTIONS
membrane
Deoxygenated Oxygenated
blood blood

Eggshells are created in such a way as to supply oxygen to the chick inside through the
porous holes. The figure above illustrates the passage of carbon dioxide, water and oxygen
through the pores.

Dense crystal layer

Inorganic spheres
layer The spongy
Shell middle part of
shell
Cones
Cones

Outer shell membrane Outer shell membrane
Inner shell membrane Inner shell membrane
The figure above shows the shell of the loon The eggs of birds living under different
egg laid on wet and muddy ground. The shell conditions vary as well. The figure above
is covered with a layer called the "inorganic shows the section of an eggshell of the
spheres layer", which prevents the pores egg of a rainbird. The specially
from closing and the chick from suffocating. crystallised outer layer protects the egg,
where it is laid in a gravel bed, against
impact and scratches.