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.
While running, the neck of a giraffe moves backward and forward to keep the animal balanced. Giraffes have a top speed of about 56 kilometres per hour (35 miles per hour), however, because its legs are so long a galloping giraffe does not appear to be going very fast.
The legs of a giraffe are also 6 feet (1.8 meters) long. The back legs look shorter than the front legs, but they are about the same length. A giraffe's heart is 2 feet (0.6 meters) long and weighs about 25 pounds (11 kilograms), and its lungs can hold 12 gallons (55 liters) of air! Its closest relative is the okapi.o, giraffes go to a watering hole together and take turns watching for predators. If water is easily available, like in zoos, they can drink 10 gallons (38 liters) a day. Many people think that giraffes have no voice, but they do make a variety of sounds, including moos, roars, snorts, hisses, and grunts.