Reading Assignment: Chapter 6--Hydromineral Balance end

Reading Assignment:

• Chapter 6--Hydromineral Balance

end

Thermoregulation:

• Cold-blooded -poor descriptor

• Poikilotherm (n); poikilothermic (adj)– variable body temperature– opposite = homeotherm

• Ectotherm (n); ectothermic (adj)– temp. determined by environment– opposite = endotherm

end

Why are fishes ectothermic?Heat generated by metabolism

skin

bodygills

end

Behavioral Thermoregulation

• nearly all fishes

• choose from available temperatures

• concept of temperature preference

end

Temperature Preference:

Temperature C0 4020

Freq

uenc

yPreferred Temperature

eurytherm

stenotherm

end

Temperature Preference continued:

Temperature C0 4020

Freq

uenc

yPreferred Temperature

cold adapted

warm adapted

end

Temperature C0 4020

Freq

uenc

yPreferred Temperature

Temperature Preference continued:

The effect of Acclimation

end

0 4020Acclimation Temperature C

Pref

erre

d Te

mpe

ratu

re C

Temperature Preference continued:The effect of Acclimation

20

0

40final preferred temperature

bluegill

temperature tolerance

end

0 4020Acclimation Temperature C

Pref

erre

d Te

mpe

ratu

re C

Temperature Preference continued:The effect of Acclimation

20

0

40final preferred temperature

chum salmon

bluegill

guppy ???

end

Physiological Thermoregulation

• few fishes--tunas & lamnid sharks

• fish are active --generate heat

• rete mirabile for heat exchange & conserv.

• fish are large--low surface area to mass ratio– body surf. area increases as square of length– body mass increases as cube of length

end

Physiological Thermoregulation

body

skin

skingills

heat

rete mirabile

end

Counter-current blood flow

Distance along capillaries (rete)

Tem

pera

ture

low

high

arterial blood

venous blood

heat

from gills

from body

end

typical

fish

tuna

Counter Current flow:

• fluid flowing in opposite directions

• exchange of heat or gas perpendicular to flow

• efficiency versus speed

end

Distance along capillaries (rete)

Tem

pera

ture

low

high

Hypothetical Co-current blood flow:

from gills

from body

arterial blood

venous bloodcounter-current

heat

end

Hypothetical Co-Current flow:

• fluid flowing in same direction

• exchange of heat or gas perpendicular to flow

• speed versus efficiency

• vessels naturally flow in opposite direction

end

end

Hydromineral Balance: Life in a solvent

Environmental forces cause movement of water and dissolved substances

versus

Homeostasis--the need to maintain balance of water and dissolved substances in cells and body fluids of organisms

-constant internal environment

end

Environmental forces:• heat--(movement of molecules) energy for

movement

• diffusion--net movement of molecules

• pressure--density of molecules – difference causes or blocks movement

• osmosis--movement of water

• electrochemical forces--attraction & repulsion of molecules based on charge

end

• Environmental forces work together toward equilibrium

• equilibrium-no net movement of molecules

end

end

Lecture Exam Monday

• 100 point exam

• covers lectures, assigned readings

• 8-12 short answer questions; 4-6 pts ea– complete, concise answer– ex: definition

• 3-5 longer questions; 10-15 pts ea

• Finish by 1:55--budget time

• Power Point lectures at: http://www.und.nodak.edu/instruct/skelsch/425~1.htm