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Warm-blooded is a term referring to animal species whose bodies maintain a temperature higher than that of their environment. In particular, homeothermic species (including birds and mammals ) maintain a stable body temperature by regulating metabolic processes.
Homeothermy is one of the 3 types of thermoregulation in warm-blooded animal species. Homeothermy's opposite is poikilothermy . A poikilotherm is an organism that does not maintain a fixed internal temperature but rather its internal temperature fluctuates based on its environment and physical behaviour.
Most mammals also have hair to help keep them warm. Like birds, mammals can forage or hunt in weather and climates too cold for ectothermic ("cold-blooded") reptiles and insects. Endothermy requires plenty of food energy, so mammals eat more food per unit of body weight than most reptiles. [ 139 ]
Small warm-blooded animals have insulation in the form of fur or feathers. Aquatic warm-blooded animals, such as seals, generally have deep layers of blubber under the skin and any pelage (fur) that they might have; both contribute to their insulation. Penguins have both feathers and blubber. Penguin feathers are scale-like and serve both for ...
The traditional "Theria hypothesis" states that the divergence of the monotreme lineage from the Metatheria and Eutheria lineages happened prior to the divergence between marsupials and placentals, and this explains why monotremes retain a number of primitive traits presumed to have been present in the synapsid ancestors of later mammals, such ...
Dinosaurs were initially cold-blooded, but global warming 180 million years ago may have triggered the evolution of warm-blooded species, a new study found.
The metabolism of archosaurs is still a controversial topic. They certainly evolved from cold-blooded ancestors, and the surviving non-dinosaurian archosaurs, crocodilians, are cold-blooded. But crocodilians have some features which are normally associated with a warm-blooded metabolism because they improve the animal's oxygen supply:
For example, the biological characteristic of warm-bloodedness evolved separately in the ancestors of mammals and the ancestors of birds; "warm-blooded animals" is therefore a polyphyletic grouping. [3] Other examples of polyphyletic groups are algae, C4 photosynthetic plants, [4] and edentates. [5]