Page 162 - Design in Nature

as the animal descends the weight of the water column above, i.e. the
pressure, increases. The pressure inside the lungs is
increased to balance the outside pressure. If the same
pressure were to be applied to human lungs, they
would easily disintegrate. In order to overcome this
danger, there is a special defensive system lodged in
a dolphin’s body: the bronchi
and air cells (alveoli) inside
the dolphin’s lungs are
protected by rings of cartilage that
are extremely durable.
Another example of the perfection of
creation in the bodies of dolphins is the system
that prevents the bends. When divers ascend
to the surface too quickly, they face this
danger. The reason for the bends is the
entrance of air directly into the blood
and formation of air bubbles in the
arteries. These air bubbles can cause
death by preventing blood
circulation. Whales and
dolphins, however, do not face
similar dangers, although they
breathe using their lungs. This
is because they dive with
lungs not full of air but
empty. Since there is no air in
their lungs, they do not