Energetics and Metabolism Activity

Humans are described in a couple of different ways in relationto maintaining body temperature: homeotherm and endotherm are twocommon phrases. “Homeotherm” translates to “same temperature,”meaning humans maintain a stable body temperature regardless of theexternal environment. Related is the term “endotherm,” meaning“internal body temperature.” Humans, being warm-blooded, aredependent and capable of internally generating heat when needed.Regardless of the phrase used, the ability to maintain a stablebody temperature is a critical part of our homeostasis. Therefore,we expend a lot of energy to maintain a near-constant internalenvironment of 37°C, which is largely accomplished by ourmetabolism.

Other organisms are poikilotherms or ectotherms; they cannotinternally regulate their body temperature, and their bodytemperature can change depending on the external environment. Mostfish, sharks, reptiles and amphibians fall into this category.While ectothermy is a significant energy-saving adaptation, it alsomeans an organism’s metabolic rate is dependent upon the externalenvironment. Higher temperatures increase metabolic rate, coldertemperatures slow it down.  

In this activity, you will be examining the effects increasedtemperature has on the metabolic rates of three species offish.

Go to the following website, and perform the experiment:

http://www.glencoe.com/sites/common_assets/science/virtual_labs/CT08/CT08.html

Fill in the table below with your results:

	Goldfish	Sun fish	Cat fish
Control (5°C)
10°C
15°C
20°C
25°C
30°C

1. Interpret your results from the experiment; what do thesedata tell you about fish metabolic rate in response totemperature?

2. How might ectotherms have to compensate for their variabilityin metabolic rate in terms of how much they eat?

3. Compare and contrast the basal metabolic rate of a fish and ahuman. How are each maintained? How might the BMR of each change ina warm environment? A cold environment?