Homeothermic animals are those that maintain a relatively constant body temperature, regardless of the ambient temperature. That its temperature is relatively constant means that it varies but within certain limits.
The majority of homeothermic animals are birds and mammals.
Methods to control body temperature regardless of ambient temperature:
- Panting : it allows to release heat.
- Burn fat : it allows to obtain heat thanks to the chemical energy stored in the fat cells.
- Increase or decrease blood flow : when blood flow is increased, more heat is released. When it is necessary to conserve heat, the body of the homeotherm animal reduces blood flow.
- Shivering : this involuntary movement of the muscles allows to increase the body temperature.
- Sweating : some animals can secrete sweat through their skin, allowing the elimination of heat.
All these mechanisms depend on the hypothalamus.
- The advantage for the homeothermic organism is that it always maintains the most favorable temperature for the chemical reactions that its metabolism must do.
- The disadvantage is that thermoregulation implies a somewhat expenditure of energy, requiring a constant consumption of food.
Examples of homeothermic animals
- Human being: Our body temperature always remains between 36 and 37 degrees. When it is too cold, we have the resource of trembling. In addition, it decreases blood flow in peripheral areas of the body, which can be seen in the tips of the fingers turn blue. When it is too hot, we have the use of sweat.
- Dog : The mechanisms of the dogs to maintain their body temperature include sweat on the legs of the legs and panting. Thanks to the panting warm blood is pumped to the tongue where the heat is removed in the form of moisture.
- Horse : Both the male horse and the mare maintain temperatures between 37.2 and 37.8 degrees, being the limit of its healthy temperature 38.1 degrees.
- Canaries : Birds do not have sweat glands, that is, they do not have sweat as a resource to lower body temperature. On the contrary, the resources of the birds are the radiation of heat through the surface of the skin, the elimination of the heat through the conduction (the contact with objects that are at a lower temperature) and the convection, that is to say the irradiation of heat in the surrounding air. That is why canaries should always be in well-ventilated environments.
- Cow : This mammal maintains a relatively constant temperature around 38.5 degrees. However, the calf (the calf of the cow) maintains a slightly higher temperature: 39.5 degrees. Cows that are raised to use their meat usually have slightly lower temperatures, between 36.7 degrees and 38.3 degrees.
- Australian Pheasant : It is the species that makes the largest nest of all birds. The female deposits the eggs and the male maintains the temperature necessary for its incubation. In addition to its body temperature, the male is responsible for maintaining the correct temperature of the nest by covering it with litter and sand when the temperature decreases and discovering it when it increases.
- Chickens : The temperature of the chickens stays between 40 and 42 degrees. However, young hens are more dependent on the ambient temperature to maintain their ideal internal temperature, so they are protected (through ventilation or placing them in closed places) if the environmental temperature is below twelve degrees or over 24 degrees. As with other birds, the constant body temperature of the hens allows them to hatch their eggs, that is, transmit an ideal temperature.
- Polar Bear : Polar bears maintain their body temperature at approximately 37 degrees. This implies a huge difference with the ambient temperature of the places where they live, which are sometimes below 30 degrees below zero. They can keep their internal temperature isolated from external temperature thanks to thick layers of hair, skin and grease.
- Penguins : Non-flying bird that can reach up to 120 cm in height. The males are the ones that incubate the eggs, during which time they do not feed, so they must obtain their food from their large reserves of fat. At the beginning of the breeding season the weight of the males is 38 kg and in the end it is 23 kg. They live in colder environments than any other bird, reaching environmental temperatures of 20 degrees below zero on average, and minimum of 40 degrees below zero. However, they maintain their constant body temperature thanks to their plumage that forms several layers on their skin, having a higher density of feathers than all other birds.