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 throughout 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.

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.

More Info: www.worldatlas.com