Reading Assignment: Chapter 16--Relict Bony Fishes end

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

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

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

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

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

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

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

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

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

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

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

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

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Growth: Longevity Note: aging with scales, bones, otoliths unconfirmed reports of carp 200-400 yr. authenticated records for carp 50 yr. large fish-few > 12-20 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

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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 end

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

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

Bioenergetic Energy Budget: heat G I M E end

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

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

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

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

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

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

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

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These will replace the diffusion and osmosis slides above. 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. end

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