33-2 Controlling Body Temperature
33-2 Controlling Body
Temperature
Body Temperature and
Homeostasis
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33-2 Controlling Body Temperature
Body Temperature and
Homeostasis
Body Temperature and Homeostasis
How is the control of body temperature
important to vertebrate life?
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33-2 Controlling Body Temperature
Body Temperature and
Homeostasis
The control of body temperature is
important for maintaining homeostasis in
vertebrates, particularly in habitats where
temperature varies widely with time of day
and with season.
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33-2 Controlling Body Temperature
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Body Temperature and
Homeostasis
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33-2 Controlling Body Temperature
Body Temperature and
Homeostasis
Ectotherms
Vertebrates have many ways to control body
temperature.
All of these incorporate three important features:
What is the difference between ectotherms
and endotherms?
•  a source of heat for the body
An ectotherm is an animal whose body
temperature is mainly determined by the
temperature of the environment.
Most reptiles, fishes, and amphibians are
ectotherms.
•  a way to conserve that heat
•  a method of eliminating excess heat when
necessary.
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33-2 Controlling Body Temperature
Body Temperature and
Homeostasis
Endotherms
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33-2 Controlling Body Temperature
Comparing Ectotherms and
Endotherms
Comparing Ectotherms and Endotherms
An endotherm is an animal whose body
temperature is controlled from within.
Neither endothermy nor ectothermy is superior. Each
strategy has advantages in different environments.
Endotherms have relatively high metabolic rates
that generate a significant amount of heat, even
when they are resting.
Endotherms do well in cool weather because they
generate and conserve body heat. However, their
high metabolic rate requires a lot of fuel.
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33-2 Controlling Body Temperature
Comparing Ecotherms and Endotherms
Ectothermic animals need much less food than
similarly sized endotherms.
In environments where temperatures stay warm and
constant, ectothermy is a more energy-efficient
strategy.
Birds and mammals are endotherms.
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