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Osmoregulation
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The problem of osmolarity:
salt water 35 ppt fresh water 0-5 ppt
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salt water fresh water 35 ppt 0-5 ppt FISHES
The problem of osmolarity: Hyper-osmotic salt water 35 ppt fresh water 0-5 ppt FISHES Hypo-osmotic fishes need to balance their internal osmotic environment increase/retain solutes, or decrease internal water - they pee a lot decrease/shed solutes, or increase internal water - they drink a lot
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salt water fresh water 35 ppt 0-5 ppt FISHES
The problem of osmolarity: Hyper-osmotic salt water 35 ppt fresh water 0-5 ppt FISHES Hypo-osmotic fishes are either: stenohaline - tolerant of limited range of osmolarity euryhaline - tolerant of wide range (where is this useful?) diadromous – osmo-adaptation changes during lifetime
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How fish deal with being osmotic misfits
1. osmo-conformers (hagfishes) maintain isosmotic conditions
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How fish deal with being osmotic misfits
1. osmo-conformers (hagfishes) 2. salt supplementers (marine elasmobranches and coelacanths) high urea content and TMAO (trimethylamine oxide) low permeability to Na+, Cl- excrete excess Na+, Cl-
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How fish deal with being osmotic misfits
3. hyposmotics (marine teleosts) tend to lose water, replace by drinking gill cells pump in water, not salts
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How fish deal with being osmotic misfits
4. hyperosmotics (freshwater fishes) excrete large volumes of water gill chloride cells pump in salts often euryhaline (striped bass, tilapia, drum)
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Diadromous fishes – experience salt and freshwater
environments during their life
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Diadromous fishes anadromous - Pacific salmon, lamprey, shad
fresh water salt water
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Diadromous fishes fresh water salt water
anadromous - Pacific salmon, lamprey, shad fresh water salt water behavioral change (drinking) changes in kidney function metamorphosis (smoltification) – cued to photoperiod, lunar cycle
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Diadromous fishes anadromous - Pacific salmon, lamprey, shad
landlocked species (potamodromous, adfluvial) - reversion of salt-water tolerance fresh water
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Diadromous fishes anadromous - Pacific salmon, lamprey, shad
landlocked species (potamodromous, adfluvial) catadromous - eels pre-leptocephalus larva mature eel leptocephalus silver eel elver, yellow eel glass eel
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The cost of osmoregulation
Kijewska et al. (2016). Adaptation to salinity in Atlantic cod from different regions of the Baltic Sea. J. Experimental Marine Biology and Ecology, 478, 62–67.
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The cost of osmoregulation
Birrer et al.(2012). Salinity change impairs pipefish immune defense. Fish and Shellfish Immunology, 33(6), 1238–1248.
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Chemoreception: taste and smell
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Taste and smell: communication
individual recognition, especially of mates species recognition, esp. schooling species offspring recognition (cichlids) scent mark territories (gobies) dominant-subordinate relationships aggression-inhibiting pheromone produced by bullheads living in groups
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Taste (= chemoreception at close range)
taste organs can reside on exterior surfaces: barbels of bottom-dwelling fishes lips of suckers over much of body of ictalurids
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Olfaction (= chemoreception at "long" range/gradients)
more sensitive than taste used for: food finding migration, e.g., salmon intra, interspecific communication
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Olfaction (= chemoreception at "long" range/gradients)
more sensitive than taste used for: food finding migration, e.g., salmon intra, interspecific communication semiochemical – chemical used for communication pheromone – elicits social response in same species kairomone – benefits receiver, not emitter – between species e.g., food, scent, necromone
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Sea lamprey, Petromyzon marinus
Sea lamprey do not (cannot) home to natal stream; and, only get one chance to spawn, so need a cue to find a good stream for spawning
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Sea lamprey, Petromyzon marinus
Petromyzonol sulfate Migratory pheromone emitted by larval lamprey – induces upstream movement of adults
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Sea lamprey sex pheromone
3kPZS Sea lamprey sex pheromone Dr. Weiming Li, Michigan State University
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Olfaction (= chemoreception at "long" range/gradients)
“Schreckstoff” alarm pheromones (Ostariophysi): Gonorynchiformes Cypriniformes Characiformes Gymnotiformes Siluriformes Note: ‘Shreck’ is German word for ‘scary’, thus ‘scary stuff’
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Olfaction (= chemoreception at "long" range/gradients)
“Schreckstoff” alarm pheromones (Ostariophysi) - originate in specialized ‘club’ cells in skin, released when fish is damaged effect is to alert other conspecifics - potent - highly specific (generally species-specific) - can pass through gut of predators intact, as warning
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Other cutaneous senses
touch few detectors – shark fins; head, barbels of bullheads mating behaviors (use of breeding tubercules) parent-young communication in catfish, cichlids, damselfishes
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Other cutaneous senses
temperature teleost cutaneous temp. sensitivity to 0.03C change can distinguish rise from a fall in temperature elasmobranchs detect temperature change with ampullae of Lorenzini
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