Page 104 - Design in Nature

CHAPTER 4

Reactive Swimming

Systems

ertebrates are the fastest running, best swimming and farthest flying
creatures on earth. The main factor underlying all of these abilities is
V the presence of skeletons made of hard materials such as the bones
that do not lose their shape. These bones provide tremendous support for
contracting and flexing muscles, which bring about continuous movements
through moving joints.
However, invertebrates move at much lower speeds, in comparison with
vertebrates, due to their boneless structures.
Cuttlefish are invertebrates that do not have bones in their bodies despite
being called fish. They have extraordinary abilities to manoeuvre because of
a very interesting system. Their soft body is covered with a thick mantle under
which large amounts of water are drawn and flushed out by strong muscles
and that enables them to escape backwards.
This mechanism in cuttlefish is
highly complex. On both sides
of the animal's head are
pocket-like openings. The water is
drawn in through these openings into a cylinder-shaped cavity
inside its body. Then, it jets out this water from a narrow pipe
immediately under its head with great pressure, which enables