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 advantage-

Animals 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 times- Heterotherms

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