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Osmoregulation
salt water35 ppt
fresh water0-5 ppt
The problem of osmolarity:
salt water35 ppt
fresh water0-5 ppt FISHES
The problem of osmolarity:
Hyper-osmotic
Hypo-osmotic
salt water35 ppt
fishes are either:stenohaline - tolerant of limited range of osmolarityeuryhaline - tolerant of wide range (where is this useful?)
fresh water0-5 ppt FISHES
The problem of osmolarity:
Hyper-osmotic
Hypo-osmotic
1. osmo-conformers (hagfishes)maintain isosmotic conditions
How fish deal with being osmotic misfits
1. osmo-conformers (hagfishes)maintain isosmotic conditions
2. salt supplementers (marine elasmobranches and coelacanths)high urea content and TMAO (trimethylamine oxide) low permeability to Na+, Cl-excrete excess Na+, Cl-
How fish deal with being osmotic misfits
1. osmo-conformers (hagfishes)
2. salt supplementers (marine elasmobranches and coelacanths)
3. hyposmotics (marine teleosts) tend to lose water, replace by drinkinggill cells pump in water, not salts
How fish deal with being osmotic misfits
1. osmo-conformers (hagfishes)
2. salt supplementers (marine elasmobranches and coelacanths)
3. hyposmotics (marine teleosts)
4. hyperosmotics (freshwater fishes)excrete large volumes of watergill chloride cells pump in salts often euryhaline (striped bass, tilapia, drum)
How fish deal with being osmotic misfits
anadromous - Pacific salmon, lamprey, shad
Diadromous fishes
fresh water
salt water
anadromous - Pacific salmon, lamprey, shad
Diadromous fishes
fresh water
salt watermetamorphosis – cued to photoperiod, lunar cycle
behavioral change (drinking)changes in kidney function
anadromous - Pacific salmon, lamprey, shadlandlocked species (potamodromous) - reversion of salt-water tolerance
Diadromous fishes
fresh water
fresh water
anadromous - Pacific salmon, lamprey, shadlandlocked species (potamodromous) - reversion of salt-water tolerancecatadromous - eels
Diadromous fishes
Credit: ICES
saltwater
freshwater
The cost of osmoregulation
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