Desert lizards rely on energy from the sun to regulate their body temperatures. Heat from the sun penetrates the skin and warms the blood, which is then circulated to the body core and other regions, warming them. When they need to cool their bodies, they move out of the sunlight until body temperatures drop. They must also, of course, be able to maintain water balance in extremely dry environments. Which of the following features would you NOT expect to find in reptilian skin?