  The bodies of snakes, such as king cobras, are very soft so that it is nearly
impossible for them to raise their heads higher than around one meter. By
direct measurement, we were only possible to hold the body of a freshly killed
cobra vertically at around 0.05 m. Here, for the first time it is reported that
the king cobra can control the effective elastic modulus of its body so that it
can raise its head up to several tens of centimeters. The effective elastic
modulus is enhanced by increasing the pressure of air trapped inside the
respiration channel, which is similar to increasing the stiffness of a thin
plastic tube by filling it with air at pressure above atmospheric pressure. The
neck height increases with the effective elastic modulus according to a scaling
relationship. It was also simply proved that the peak of force or constriction
pressure is proportional to the snakes diameter. This work may provide a
physical foundation underlying the mechanical properties of slender animals.
