Reading Assignment:

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Reading Assignment

• Chapter 16--Relict Bony Fishes

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Passive processes

• Diffusion, osmosis, pressure, molecular
  movement from electrochem. Forces are passive
  processes
• require no energy from organism
• Active Processes-those that require organism to
  expend energy.
• needed for homeostasis to counter some passive
  processes

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Definitions

• Ionic Regulation maintenance of concentrations
  of specific ions
• Osmoregulation maintenance of constant
  concentrations of total dissolved substances in
  extracellular fluids

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Four osmoregulatory strategies in fishes

• 1. Isosmotic (nearly isoionic)
• essentially no regulation
• body fluids same osmotic conc. as environment
• advantages and disadvantages?
• Examples many inverts. Hagfishes only marine
  spp.

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Four osmoregulatory strategies in fishes
continued

• 2. Isosmotic with regulation of specific ions
• organic salts stored in extracellular fluids
  (prim. urea)
• Inorganic salt conc. approx. 1/3 seawater
• rectal gland secretes Na and Cl- in conc close
  to that of seawater (active process)
• advantages and disadvantages?
• Examples elasmobranchs, coelacanth (marine)

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Four osmoregulatory strategies in fishes
continued

• 3. Osmotic ionic regulation by marine teleosts
• ionic conc. Approx 1/3 of seawater
• drink copiously to gain water
• Chloride cells eliminate Na and Cl-
• kidneys eliminate Mg and SO4
• advantages and disadvantages?
• Examples saltwater teleosts

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Saltwater teleosts
H2O
drink
Na, Cl-
Na, Cl-
Mg, SO4
Na, Cl- Mg, SO4
kidneys
chloride cells
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Chloride Cell fig 6.2
sea water
charge
charge

2Cl-
Na
Na K ATPase
K
Na,K
mitochondria
internal (blood)
tubular system
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Four osmoregulatory strategies in fishes
continued

• 4. Osmotic ionic regulation by FW teleosts
• ionic conc. Approx 1/3 of seawater
• dont drink
• Chloride cells fewer, work in reverse
• kidneys eliminate excess water ion loss
• ammonia bicarbonate ion exchange mechanisms
• advantages and disadvantages?
• Examples FW teleosts FW elasmobranchs

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Freshwater teleosts
Ion exchange pumps beta chloride cells
kidneys
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Ion Exchange Mechanisms
freshwater
interior
Na?
active pump
ATP
Cl-?
active pump
ATP
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Freezing Resistance

• What fishes might face freezing?
• hagfishes?
• isotonic
• marine elasmobranchs?
• isotonic
• freshwater teleosts?
• hypertonic
• marine teleosts?
• hypotonic

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Solution for cold-adapted marine teleosts

• Macromolecular antifreeze compounds
• peptides (protein)
• glycopeptides (carbohydrate/protein)

• molecules adsorb to ice crystal surface
• interfere with ice crystal growth
• ice ruptures cells interferes with osmotic
  balance

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Growth

• Longevity
• unconfirmed reports of carp 200-400 yr.
• authenticated records for carp 50 yr.
• large fish-few gt 12-20 yr.
• some marine spp gt 100 yr. thornyspines, orange
  roughy
• many small spp-2 yr. or less (sardines,
  anchovies)
• Note aging with scales, bones, otoliths

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Growth Other Generalities

• females often larger than males
• growth rate varies with temp.
• longevity inversely proportional to temp.
• stress reduces growth
• dominance hierarchies - dominant get food
• overcrowding can lead to stunting
• indeterminate growth - grow throughout life
• growth highly variable - can loose weight

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Bioenergetic Definition of Growth

• energy accumulation (calories) vs. length or
  weight

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Bioenergetics continued

• Energy Budget
• I M G E
• where I ingested energy
• M energy expended for metabolism
• G energy stored as growth
• E energy lost to environment

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Bioenergetic Energy Budget
I
E
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Bioenergetics continued

• Ex M energy for body repair
• maintenance
• activity
• digestion

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Bioenergetics continued

• Ex E energy in feces
• ammonia, or urea
• mucus
• epidermal cells

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Terms

• Standard Metabolic Rate
• maintenance met. no growth, no activity
• Routine Metabolic Rate
• typical met. routine growth activity
• Active Metabolic Rate
• max. aerobic metabolism

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Factors Affecting Growth Temperature
routine
active
standard
scope
Metabolic Rate
activity
growth
Where would growth be best?
Temperature
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Factors Affecting Growth Temperature
normal O2
reduced O2
Metabolic Rate
reduced scope
reduced growth
Temperature
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Growth will not occur at low O2
Ex LMB cease growing below 5 mg/L
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Factors Affecting Growth Dissolved oxygen
Routine Metabolism
critical O2 concentration
Dissolved Oxygen mg/L
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• The following slides are animated with a feature
  that does not work on powerpoint2000. save for
  use when 105 gets ppxp
• These will replace the diffusion and osmosis
  slides above.

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substance
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substance