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15 Cards in this Set

  • Front
  • Back
O2 availability
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
O2 binding proteins in body
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
Behaviour of pigments in response to circumstances
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
Hypoxic, low O2
Ca+ and lactate builds
Changes folding pattern and shape of hemocyanin, increased O2 affinity
Allows 36-60 hour survival in near anoxic conditions
Euryhaline marine species
Tolerate reduced salinity
Salinity changes
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
Behavioural solutions to change oxygen availability
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
Stenohaline marine species
Can't tolerate reduced salinity
Osmoregulation
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)
Osmoregulation in Neresis diversicolour
Placed in freshwater, weight incr as water taken in, weight gradually reduced by weak osmoregulation
Salt excreted through nephridiopores
Regulation weak in low salinities
Change of behaviour due to change in salinity
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
Water movement
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
Food supply stresses
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
Competition for space
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
Predation
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