Population ecology is the study of these and other questions about what factors affect population and how and why a population changes over time. Population ecology has its deepest historic roots, and its richest development, in the study of population growth, regulation, and dynamics, or demography.
When giraffes walk, they move both legs on one side of their body and then both legs on the other side; this is unique to giraffes. However, they run in a similar style to other mammals, swinging their rear legs and front legs in unison. They can reach 55 km/h (35 mph) at full speed but only in brief spurts.
The first is the faster belly run which I've already mentioned, in which the legs move very rapidly in a typically reptilian pattern to propel the crocodile forward. During this belly run, the crocodile starts to move its body in a sinusoidal manner along the horizontal plane, almost as if it were swimming.