Endothermic (Warm Blooded) Animals

5. Defining Endothermic Animals

Endothermy is a feature that appeared late in the evolution of animals, and is found only in modern animals. Warm-blooded animals are also called endothermic or homoeothermic animals, and they generate heat internally and have a thermoregulatory system that maintains a constant body temperature largely independent of their surroundings. They also tend to maintain the same temperature through out their lifetime. Warm-blooded animals use most of the food they eat to convert it to energy to stay warm, with the help of mitochondria found in each cell. Only a small amount of food they eat is converted to body mass. Smaller animals in particular have to feed intensively, especially food with high energy contents, such as seeds, insects, or other smaller animals. The larger animals need less food. Usually the body temperature is more than the surroundings. It is more difficult for warm-blooded animals to loose warmth than to stay warm.

4. Notable Examples

Humans, which are warm-blooded, maintain a constant temperature of around 37° Celsius. Most mammals, small and big, as well as many birds, are warm-blooded animals. Therefore all primates (such as humans, apes, and monkeys), cats (tigers, cheetahs, and domestic cats), rodents (rats, beavers, and chipmunks), marsupials (kangaroo), weasels (badgers and meerkats), monotremes (platypuses), sea mammals (whales, seals, walruses, manatees, and dolphins), dogs, pigs, and elephants are warm-blooded. Some birds, however, are not warm-blooded. Moreover, some other mammals, such as bats, mole rats, and echidnas, are neither warm-blooded or cold-blooded.

3. Evolutionary Adaptation Mechanisms

Since they are not dependent on the surrounding environment to maintain their body temperatures, warm-blooded animals can live in both warm and cold places. They have various strategies to preserve warmth, including a thick fur which they may grow in winter and shed in summer, or the feathers of a bird, or the blubber in sea mammals. There are also various behavioral responses including shivering, migration, or hibernation in cold temperatures. Some birds migrate over thousands of kilometers to get stay in places of optimum temperatures. There are also many small birds, and mammals that are known to hibernate even though they are warm-blooded, such as the California mouse and the kangaroo mouse. Sweat glands are used to lose heat; in primates and humans these are present all over the body, while in cats and dogs the glands are found only on the feet. Panting is another mechanism to lose heat.

2. Benefits Of Endothermy

Warm-blooded animals generally do not have to hibernate besides a few exceptions, and they can be active throughout the year, feeding, moving, and protecting themselves from predators. Though the warm-blooded animals have to consume a lot of food to remain active, they have the energy and means to colonize all kinds of environments, even in cold Antarctica or in higher mountain ranges. They can also move longer distances and are faster than cold-blooded animals.

1. Disadvantages Of Endothermy

Since the body temperatures of warm-blooded animals remain stable, they provide suitable living conditions for many parasites, such as worms, or micro-organisms including bacteria and viruses, many of which can cause fatal diseases. As the warm-blooded animals generate their own heat the body ratio of weight to surface is also important. A larger body mass produces more warmth, so a large body surface is used to lose heat in summer or in warmer places, therefore the big ears in elephants. Therefore, warm-blooded animals cannot be as small in body size as cold-blooded insects can be.