Endotherms

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Chapter 4 - Temperature
Question?
Along the shoreline of Lake
Michigan in Michigan, fruit trees
are grown in abundance. These
plants are not found 20 or 30
miles inland from the lake.
Why?
Chapter 4 - Temperature
Objectives:
1. Identify where heat comes from and where
is goes!!!
2. Describe how organisms compensate for
variations in environmental temperatures
3. List similarities and differences between
ectotherm and endotherm
4. Define resting stages and their applications
Temperature - The Formula
Hs = Hm + Hcd + Hcv + Hr + He
Where:
Hs = Total heat stored in body
Hm= Heat gained from metabolism
Hcd = Heat gained or lost from conduction
Hcv = Heat gained or lost from convection
Temperature - The Formula
Hs = Hm + Hcd + Hcv + Hr + He
Where:
Hr = Heat gained or lost through
electromagnetic radiation
He = Heat lost through evaporation
Fig. 4.13
Thermal Control
Organisms can control body temperature by:
• Amount of surface area exposed to sun
• Amount of body surface exposed to
cooler/warmer surfaces
• Thermal conductivity of body surface (fluff
fur or feathers
Thermal Control
• Amount of stored chemical energy released
by metabolism
• Amount of water evaporated from the body
• Amount of sunlight reflected from their
surface
Physiological Response to
Temperature
Organisms whose body temperature varies in
directly with environmental temperatures -
Don’t you mean: cold-blooded?
Poikilotherms
Animals--- many aquatic: clams,
worms, insect larvae, barnacles,
Plants--- aquatic: phytoplankton,
Others--- bacteria, fungi
Poikilotherms
Advantages:
Can allocate more energy to growth and
reproduction
Can colonize areas of limited food and water
Expending no energy maintaining a
temperature different than the environment
Poikilotherms
Disadvantages:
Activities restricted to warmer days and
seasons
Limited ability to colonize colder regions
Ectotherms
Organisms that rely on external sources of
heat to regulate body temperature, usually a
combination of behavior, and anatomy
Ectotherms
How does this happen?
Plants:
• Orientation to or away from the sun,
pigmentation (radiation)
• Loss of water through leaves (evaporation)
• Altering wind patterns using growth forms
(convection)
Fig. 4.14
Fig. 4.15
Fig. 4.16
Ectotherms
Animals:
Similar to plants-body size, shape, and
pigmentation
One big advantageAnimals can move to find different
microclimates to best suite their needs
Fig. 4.17
Endotherms
• Similar to ectotherms; that
is, they use the environment
to warm and cool the body.
• But-- Rely extensively on
metabolic heat to regulate
the body temperature.
Endotherms
Below what temperature do you
need to put on a coat?
Above what temperature would
you like to have air
conditioning?
Endotherms
Thermal neutral zone:
Range of temperature over which metabolic
rate of endotherm does not change
“Comfort
Zone”
Fig. 4-21
Endotherms
Advantages:
Can maintain activity over a wide range of
temperatures
Efficient respiration enables long periods of
activity
Can colonize a wide range of environments,
including e.g., polar regions
Endotherms
Disadvantages:
Must expend energy to maintain body
temperature
May require large amounts of water to
maintain body temperature in hot
environments
Endotherms
Regulate their body temperature within a
narrow range, independent of the
environment Homeotherms
e.g., mammals and birds ~ 35-40 C
Warm-blooded????
Endotherms
Organisms that control their body temperature
some of the time, while allowing it to be
controlled by the environment other timesHeterotherms
e.g., animals that hibernate - bats, marmots,
hummingbirds, But Not Bears
Reducing Metabolic Rate
What is it?
A state of low metabolic rate and low body
temperature. Organisms rely on stored
energy reserves.
“Torpor”
Reducing Metabolic
Rate/Temperature
Daily or for several hours at a time:
“Torpor” e.g., hummingbirds
Extended period of time in winter
“Hibernation” e.g., marmots
Extended period of time in summer:
“Estivation” e.g., turtles
Fig. 4.29
Assignment
For Thursday
Read Chapter 5 - Water Relations
Did we learn anything today?
1. Identified how some organisms compensate
for variations in environmental temperatures
2. Know what the terms ectotherm,
endotherm, homeotherm, heterotherm mean
3. Understand hibernation and torpor
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