Animal Form and Function: Principles, Thermoregulation, and Energy ...

In this video I discuss the main principles that govern an animal's form and interactions with its environment. The cells in animals are bathed in interstitial fluid, which describe the animal's internal environment. Animals such as mammals and birds are termed regulators because they are able to maintain a constant internal body temperature despite their changing environments. Animals such as most fish and reptiles are termed conformers because they adapt their internal environment to match the external environment. The degree to which animals maintain their internal environment, either via thermoregulation or behavior regulation, range between homeothermic (narrow change) and poikilothermic (wide change).

The energy use, in terms of consumption of oxygen, does not vary linearly with animal size or even the type of energy expenditure. For example, mice use up energy at 3 times the relative rate as rabbits. And human running consumes oxygen linearly with speed, while birds flying consume energy in a U-shape: high energy at low speeds to maintain flight, less energy at medium speeds because of the additional lift from the wind, and high energy use at high speeds to overcome air resistance.

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Time stamps

Cells in each animal body are bathed in interstitial fluid, and define the animal's internal environment: 0:00
Distribution of the total body water in mammal: 3:28
Thermoregulation is ability to keep its body temperature within certain boundaries: 7:24
Many reptiles / lizards regulate body temperatures within a narrow range by constantly moving between sun and shade, and other mechanisms: 9:48
Only birds and mammals are universally endothermic groups of animals: 12:00
Many terrestrial ectotherms are poikilothermic: 15:12
Comparison between endothermic, ectothermic, homeothermic, and poikilothermic: 16:37
Pacific bluefin tuna produces its own heat heat can survive deep dives that temporarily chill its heart: 19:36
Homeostasis is the stability of animal's internal environment via feedback loops: 22:19
Terrestrial or land animals' use of energy does not scale linearly with size: 24:53
Running consumes oxygen linearly, swimming is exponential, and flying is U-shaped: 26:54