Explain how dark color may be beneficial to a darkling beetle and a phainopepla. Many animals go below ground during the heat of a summer day. Describe the benefits of such retreats. Bergman's rule states that animals of warmer regions tend to have smaller body sizes. Describe the thermoregulatory and energetic explanations for this trend.
Rattlesnakes are active primarily at night during warmer months.
Even in absolute darkness, rattlesnakes can detect their warm-blooded prey, rodents being a favorite meal. Consider a large lizard. Describe how vasoconstriction and dilatation can enhance both heat gain and heat loss. Include hypothetical situations to help illustrate how controlling skin blood flow can be beneficial. As a reptile basks in the sun the head can warm faster than deeper body tissues.