Warm-blooded animals have a constant steady body temperature, which does not depend on the ambient temperature. In cold-blooded animals body temperature changes depending on the ambient temperature.
Warm-blooded animals are mammals and birds. All other vertebrates (amphibians, reptiles, fish) and all invertebrates are cold-blooded.
In cold-blooded animals slower processes of metabolism, which is 20-30 times slower than in warm-blooded! Therefore, their body temperature above the ambient temperature to a maximum of 1-2 degrees. Cold-blooded animals are active only in the warmer months. When the temperature decreases, the cold-blooded animals decreases the speed (you probably noticed, "sleepy" flies, bees, or butterflies in the fall?) In winter, they fall into a state of suspended animation, that is in hibernation.
A warm-blooded system is considered more advantageous property of the organism from the point of view of evolution, as it allows to exist in various climatic conditions and to remain active in the cold and in the hot season. Provides a warm-blooded system mechanisms of thermoregulation. There are three main ways of thermoregulation:
1. Chemical thermoregulation is the increased production of heat in response to lowering of the temperature of the environment.
2. Physical thermoregulation - change the level of heat. Physical thermoregulation is provided not at the expense of additional heat, and by keeping it in the body of the animal, by reflex contraction and expansion of blood vessels of the skin (it changes its conductivity), changes in heat-insulating properties of fur and feather coat, regulation of evaporative heat loss. The thick fur of mammals, feathers in birds allow you to save around the body, a layer of air with a temperature close to body temperature of the animal, and thereby to reduce the heat loss to the external environment. The inhabitants of cold climates well developed layer of subcutaneous fat, which is evenly distributed throughout the body and is a good heat insulator.
Excellent regulation mechanism of heat transfer is also the evaporation of water by sweating. People with strong heat can allocate more than 10 liters of sweat per day! Sweating helps to cool the body.
3. Behavioral thermoregulation (for example, when the animal tries to avoid extreme temperatures, moving in space).
Maintaining a high body temperature is ensured by the fact that in the cold the processes of heat production in the body prevail over the processes of heat transfer. But maintaining temperature by increasing heat production requires large power consumption, so the animals in the cold period of the year need large amounts of food or spend a lot of fat reserves they have accumulated during the summer. So, for example, birds that remain to winter, terrible not so much cold as hunger. And it is because of lack of food, and not because of the cold hibernate in winter some warm-blooded animals, such as bears.
Do cold blooded no advantages over warm-blooded? Of course, there is! It is no accident that cold-blooded animals on our planet are more numerous than warm-blooded. The advantage of cold-blooded in that warm-blooded animals to maintain a constant high body temperature requires a lot of energy, food, and during its deficit during the cold snap they just die, and cold-blooded can safely survive the cold, lying outwards into hibernation. So, for example, almost bare cold-blooded amphibians are ubiquitous animals able to live in all parts of the world, except Antarctica!