Ectotherm- an animal whose body temperature changes with the temperature of its surrounding environment. Endotherm- an animal whose body temperature does not change with its surrounding environment. Ectotherms are animals like snakes and lizards that change their body temp with the ambient temperature. Endotherms are humans and other mammals like birds that keep there body temperature the same no matter what the climate is like. The process of homeostasis regulates our body temperature through negative feedback. For example, when our body temperature decreases due to the cold environment, we shiver to increase the body temperature. When the body temperature increases, we sweat to decrease the body temperature.