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15 Cards in this Set
- Front
- Back
O2 availability
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Low in fine sediment, decreases deeper down
Fine sand restricts water flow and gas exchange Sediment rich in food can be O2 poor and toxic (H2S) Concentration falls with increasing temperature Siphons help retain contract with well oxygenated water Increase gas exchange surface area, tentacles, gills |
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O2 binding proteins in body
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Haemocyanin: copper, clear/blue, suspended in haemolymph, molluscs, arthropods
Haemerythrin: iron, clear/violet, bound to cells in blood, annelids, lamp shells Chlorocruonin: green/red, suspended in haemolymph, polychaete worms Haemoglobin: iron, bound to cells, suspended, vertebrates, polychaetes, nematodes, echinoderms |
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Behaviour of pigments in response to circumstances
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Curve left: pigment takes up O2 more easily at low pressure, lugworm, higher affinity, incr pH, decr temp, O2 binds, in gills
Curve right: pigment gives up O2 to tissues more easily, active foragers, lower affinity, O2 release, incr temp, decr pH, in tissue |
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Hypoxic, low O2
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Ca+ and lactate builds
Changes folding pattern and shape of hemocyanin, increased O2 affinity Allows 36-60 hour survival in near anoxic conditions |
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Euryhaline marine species
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Tolerate reduced salinity
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Salinity changes
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Estuary influx of freshwater reduces salinity
- conc salt greater outside, water flows in, cells pop Tidal region evaporation at low tide increases salinity - conc salts greater outside, water flows out, dehydration |
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Behavioural solutions to change oxygen availability
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Active movement of water to maintain fresh O2 supply, can live in de-oxygenated deposits by pumping O2 forward along the burrow using peristaltic waves
Bursts of headward irrigation uses O2 in gallery, stops, moves to surface and deposits worm cast, returns bringing fresh water supply, every 15-40 mins Move to area of higher O2 Decrease O2 required in hypoxic conditions |
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Stenohaline marine species
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Can't tolerate reduced salinity
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Osmoregulation
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Reduce change, costs energy, preserves function
Control salt/water movement Regulate conc of organic osmolytes (urea) or free amino acids Reduce skin permeability Limit area of exchange to a single organ (kidney, gills) |
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Osmoregulation in Neresis diversicolour
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Placed in freshwater, weight incr as water taken in, weight gradually reduced by weak osmoregulation
Salt excreted through nephridiopores Regulation weak in low salinities |
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Change of behaviour due to change in salinity
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Live in estuary system have to tolerate wide range
Burrow into mud when large amounts of freshwater Avoid exposure to low salinity Bivalves shut shells |
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Water movement
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Sessile suspension feeders need to withstand water force and extract maximum food
Reduce surface area exposed but max area better for food Branches leave gaps for flow Protein skeleton more flexible Catch connective tissue reduces cost of cross-current orientation |
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Food supply stresses
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Suspended in water, on rocks, in sediment
Population density can match food availability Choose where to settle based on nutrients Population incr faster than supply? Why die if don't need to? Mud dogwhelks larvae: cues signal when to settle and metamorphoses More larvae settle where natural substrate |
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Competition for space
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Dominant can exclude other species
Chthamalus barnacles: higher on shore, better at dessiccation Semibalanus: superior lower down shore Dessiccation higher at lower latitudes so Ch better |
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Predation
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Many slow-moving/sessile species easy targets
Burrow into sediment: razor clam Tube of mucus and grit: sand mason worm Calcified tube or shell: CaCO3, common, molluscs Camouflage: crypsis and mimicry |