Reading Assignment:

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Reading Assignment

• Chapter 6--Hydromineral Balance

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Thermoregulation

• Cold-blooded -poor descriptor
• Poikilotherm (n) poikilothermic (adj)
• variable body temperature
• opposite homeotherm
• Ectotherm (n) ectothermic (adj)
• temp. determined by environment
• opposite endotherm

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Why are fishes ectothermic?
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Behavioral Thermoregulation

• nearly all fishes
• choose from available temperatures
• concept of temperature preference

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Temperature Preference
Frequency
Temperature C
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Temperature Preference continued
cold adapted
warm adapted
Frequency
Temperature C
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Temperature Preference continued
The effect of Acclimation
Frequency
Temperature C
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Temperature Preference continued
The effect of Acclimation
bluegill
temperature tolerance
Preferred Temperature C
Acclimation Temperature C
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Temperature Preference continued
The effect of Acclimation
bluegill
???
guppy
Preferred Temperature C
chum salmon
Acclimation Temperature C
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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

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Physiological Thermoregulation
skin
gills

body

skin
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Counter-current blood flow
from body
high
heat
venous blood
Temperature
arterial blood
from gills
low
Distance along capillaries (rete)
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Counter Current flow

• fluid flowing in opposite directions
• exchange of heat or gas perpendicular to flow
• efficiency versus speed

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Hypothetical Co-current blood flow
from body
high
counter-current
venous blood
Temperature
arterial blood
from gills
low
Distance along capillaries (rete)
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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

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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

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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

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• Environmental forces work together toward
  equilibrium
• equilibrium-no net movement of molecules

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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 155--budget time
• Power Point lectures at
• http//www.und.nodak.edu/instruct/skelsch/4251.ht
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