**3. Endotherms**

Evaporative cooling, relying on environmental or body water, is an important mechanism used by many endotherms to avoid overheating. Numerous species have evolved behaviors that facilitate heat loss or minimize heat gain from solar radiation. Evaporation can occur passively through the skin of mammals and birds. Animals lacking sweat glands rely on saliva spread onto the surface of their body or may pant. By changing their posture or orientation to the sun, some animals expose a larger percentage of their surface area to cooler substrates allowing heat to be conducted away from their bodies. Solar radiation correlates with changing postures or orientations to reveal more of their surface area and is employed by some species such as sea lions to increase or decrease exposure to solar radiation. Anteaters, whose prey is not very energy rich, often use solar radiation to offset metabolic costs of thermoregulation by avoiding sunlit areas on hot days. They also switch their foraging behavior to nocturnal periods when days are exceptionally hot (de Sampaio et al., 2006).
