Physiological Ecology of Animals

Terms:
heterotroph, ectotherm, endotherm, poikilotherm, homeotherm, conduction, convection, thermoregulation, thermal neutral zone, homeostasis, hypothermia, hyperthermia, Bergmann's Rule, countercurrent heat exchange, hibernation, torpor, supercooling

Bergmann's Rule:  States that populations of a widespread organism will have larger body size in colder regions and smaller in warmer due to heat exchange and surface area/volume relationships.

conduction: Thermal exchange between two surfaces by direct contact between them.

convection:  Thermal exchange between two substances (solid, liquid, or gas) where one or both substances also is moving.

countercurrent heat exchange:  Using a close association of arteries and veins in an extremity, such as a flipper, to transfer heat from blood at the body core to cooled blood coming from extremity.

ectotherm: An organism whose body temperature fluctuates with environmental temperature as it cannot generate constant internal heat.

endotherm: An organism that is able to generate internal heat and maintain a constant body temperature.

heterotroph: An organsism that must obtain its energy from other organisms as it is unable to complete photosynthesis.

hibernation: A long-term drop in body temperature, usually preceded by gradual physiological changes in relation to seasonal changes and photopheriod, used by endotherms to conserve energy in extreme environments.

homeostasis:  The maintenance of constant conditions within an organism, such as constant body temperature, levels of cellular fluids, dissolved salts, etc. 

homeotherm: Constant heat, refers to endotherms since they can maintain a constant body temperature despite environmental temperatures.

hyperthermia: At high environmental temperatures, when an endotherm must increase metabolic rate to maintain constant body temperature, but fails to do so and its temperature continues to rise until death.

hypothermia: At low environmental temperatures, when an endotherm must increase metabolic rate to maintain constant body temperature, but fails to do so and its temperature continues to fall until death.

poikilotherm:  Changeable heat, refers to ectotherms since they have a body temperature that fluctuates with the environment.

supercooling: When a plant or animal increases concentrated salts, sugars, or other nutrients in its cells to help avoid cellular freezing and to acclimate to colder temperatures.

thermoregulation: The regulation of body conditions (temperature, salt concentratins, water) in an organism through behavioral or physiological responses to changing environmental conditions.

thermal neutral zone: The environmental temperature range under which an endotherm can maintain constant body conditions at the lowest metabolic rate and rate of energy consumption.

torpor:  A nonseasonal, temporary drop in body temperature and metabolic rate to save energy during periods of stress (cold temperatures, lack of food, water, etc.).