Referring to Figure 16-2 it is apparent that the three tortoise species have adapted different shell shapes. The first species has a high arched shell while the second species has a lower flatter shell. The third tortoise species has a shell that is somewhere in between the first two in terms of height.
It is believed that the different shell shapes of the three tortoise species are due to the different environments in which they live. The first tortoise species lives in a dry desert-like environment where the high arched shell helps to protect it from the hot sun. The second tortoise species lives in a wetter more forested environment where the lower flatter shell helps it to stay hidden from predators. The third tortoise species lives in a transitional environment between the desert and the forest and so has adapted a shell that is a compromise between the two extremes.
The different shell shapes of the three tortoise species are just one example of the many ways in which these animals have adapted to their different environments. Other notable examples include the difference in the size and shape of their head and feet and the thickness of their shells.
