1. Reading Assignment:
Chapter 16--Relict Bony Fishes
end

2. 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
end

3. Definitions:
Ionic Regulation: maintenance of concentrations of specific ions
Osmoregulation: maintenance of constant concentrations of total dissolved substances in extracellular fluids
end

4. 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.
end

5. 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)
end

6. 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
end

7. Saltwater teleosts: active passive H2O drink Na+, Cl- Na+, Cl-
Mg++, SO4=
Na+, Cl-
Mg++, SO4=
chloride cells
kidneys
end

8. Chloride Cell fig 6.2: + active passive sea water gut chloride cell
charge PC
Na+, Cl-
pavement
cell
chloride cell
charge
accessory
cell PC
Cl-
Na+ +
gut
carrier
2Cl-
pump
Na+
Na+ K+ ATPase
Na+,K+ K+
ion channel
mitochondria
internal (blood)
tubular system
end

9. Four osmoregulatory strategies in fishes continued:
4. Osmotic & ionic regulation by FW teleosts
ionic conc. Approx 1/3 of seawater
don’t 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
end

10. pumps; beta chloride cells
Freshwater teleosts:
active
passive
H2O
don’t
drink
Na+, Cl-
Na+, Cl-
water
Ion exchange
pumps; beta chloride cells
kidneys
end

11. Ion Exchange Mechanisms
freshwater
interior
gill membrane
Na+?
Na+
active
pump
ATP
Cl-?
NH4+ or H+
Cl-
active
pump
ATP
HCO3-
end

12. Freezing Resistance: What fishes might face freezing? hagfishes?
isotonic
marine elasmobranchs?
freshwater teleosts?
hypertonic
marine teleosts?
hypotonic
end

13. Solution for cold-adapted marine teleosts:
Macromolecular antifreeze compounds
peptides (protein)
glycopeptides (carbohydrate/protein) {
rich in alanine
molecules adsorb to ice crystal surface
interfere with ice crystal growth
ice ruptures cells; interferes with osmotic balance
end

14. end

15. Growth: Longevity Note: aging with scales, bones, otoliths
unconfirmed reports of carp yr.
authenticated records for carp 50 yr.
large fish-few > yr.
some marine spp > 100 yr. thornyspines, orange roughy
many small spp-2 yr. or less (sardines, anchovies)
Note: aging with scales, bones, otoliths
end

16. end

18. 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
end

19. Bioenergetic Definition of Growth
energy accumulation (calories) vs. length or weight
end

20. 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
end

21. Bioenergetic Energy Budget:
heat G I M E
end

22. Bioenergetics continued:
Ex: M = energy for body repair
maintenance
activity
digestion
end

23. Bioenergetics continued:
Ex: E = energy in feces
ammonia, or urea
mucus
epidermal cells
end

24. Terms: Standard Metabolic Rate Routine Metabolic Rate
maintenance met.; no growth, no activity
Routine Metabolic Rate
typical met.; routine growth & activity
Active Metabolic Rate
max. aerobic metabolism
end

25. Factors Affecting Growth: Temperature
routine
active
standard
scope
Metabolic Rate {
activity
growth
Where would
growth be best?
Temperature
end

26. Factors Affecting Growth: Temperature
normal O2
reduced O2
Metabolic Rate
reduced scope
reduced growth
Temperature
end

27. Growth will not occur at low O2
Ex: LMB cease growing below 5 mg/L
end

28. Factors Affecting Growth: Dissolved oxygen
O2 regulator (most species)
Routine Metabolism
O2 conformer
critical O2 concentration 8 4
Dissolved Oxygen mg/L
end

29. end

30. These will replace the diffusion and osmosis slides above.
The following slides are animated with a feature that does not work on powerpoint save for use when 105 gets ppxp
These will replace the diffusion and osmosis slides above.
end

31. water
substance
end

32. water
substance
end

33. water
substance

34. water
substance

35. water
substance

36. water
substance