- supports bottom living organismsHowever, tissue is slightly more dense than surrounding SW so without special adoptions, organisms would sunk.
- lowers energy spent by swimming organisms
Portuguese man - of - war and By - the - Wind - sailor secrete gases into a float so they float - also acts as sail.
Snails float by producing gas bubbles in intestine or form bubble rate to float at surface - shell very thin, light and fragile.
Algae secrete gas bubbles or have gas filled floats to keep them in sunlit surface waters to maximize photosynthesis.
Cephalopods chambered nautilus and cuttle fish regulate buoyancy.
Nautilus Secretes Chamber in shell - lives in outer chamber - Chambers filled with N2
Cuttle fish has soft internal shell - controls buoyancy by regulating the amount of gas and water in shell.
Fish - gas filled swim bladder -
Continuously swimming predators, mackerel, tuna, sharks - have no swim bladder - neither do bottom fish.
Small phytoplankton and zooplankton synthesize oil droplets incorporated in cells to decrease density and slow sinking
- also have large surface area : volume
- dependent on small size
- also developed cellular processes - spines, appendages that increase surface area and slow sinking.
Large Marine animals - tissue more dense than SW.
Whales, seals increase flotation by storing large amount of blubber ( low density fat).
Sharks and some other fish store oil in liver and muscle.
Seabirds - fat deposits, light bones and air sacs, water
- salt content of SW provides increased buoyancy but differs from salt content of body fluids of osmoregulators, e.g. fish - have salt concentration between FW and SW
- in SW, Lose water by osmosis from high water conc. inside to low water conc. outside.
Fish must constantly use energy to maintain ionic homeostasis.
SW fish drink continuously and excrete excess ions across the gills and in concentrated urine.
Sharks and rays have same osmotic concentration in body fluids as in SW
- Maintain high urea levels - allows tissue to retain
water, prevents salt uptake
- most inverts
- body fluids in equilibrium with salt content over wide range.
Salinity may limit distribution of organisms
- since salinity is constant in deep waters, species living below surface layer are widely dispersed.
Surface organisms often find salinity barriers in coastal
- salinity in bays and estuaries may fluctuate
- most successful estuarine animals are good osmoregulators.
- salmon - anadromous fish.
Density of SW is affected by temp and salinity. In polar waters, surface water is cold and dense but in tropical waters, warm water is less dense.
- tropical organisms usually hade more appendages, produce more gas bubbles, have larger surface areas than similar species in polar waters.
Temp has a large effect on metabolism
- cold blooded animals - body temp varies with environmental conditions.
cold water forms in general grow slower, live longer and grow larger than warm water forms
- also distribution of temp. in the oceans limits distribution of marines organisms - both vertically and horizontally.
Tuna - exploits thermocline to feed because of heat conservation
and generation in muscles and brain.
Pressure may alter metabolic rates but deep living organisms have no gas - filled chamber to maintain a high pressure
Air breathing mammals
- dive deep for a long time with no problems
- blood absorbs more O2 and tolerates more CO 2 than land mammals.
- vascular shut directs blood plow to hear and brain - away from periphery
- lungs collapse during dive, forcing our air out and preventing blood form absorbing gas at high pressure.
- Vertical distribution Pelagic environments
Neritic ( inshore )
- Organisms / living in water column - not on the bottom
- ties to water column - depend very little on substrate
Neritic province - in shore
- covers continental shelf and water above it
- extends form MLW to end of shelf
- max depth 200 m - but varies with oceans because of variations in width of shelves
e.g. California shelf - few miles
west coast of FL - 60 miles.
OCEANIC PROVINCE- blue water
- offshore from edge of continental shelf to >7,000 - 10,000 m
- total diurnal and seasonal movement of pelagic organisms into neritic realm due to fluctuations in current strength.
Mesopelagic (200m to 1000m)
- corresponds to depth of neritic ( 200m)
- photic zone
- fairly constant salinity
- good mixing - high productivity
- low nutrients - removed rapidly by high surface productivity.
- twilight zone
- light begins to disappear until it cannot be detected at 100 m
- below layer of wind mixing
- affected by thermohaline circulation
- temp. changes rapidly - from 10 - 4 C
- vertically no seasonal change in temp, light or salinity
- high nutrients - not utilized because productivity is very low - not enough light.
Bathypelagic - 100 - 400 m - uniform condition most of the ocean.
Abyssopelagic ( below 400m) trenches - similar physically to bathypelagic. Small populations of swimming inverts; food is scarce.
- constant temp 2-4C
- no light
- high nutrients.
- mostly soft bodies, large predators with bizarre devices for feeding and reproduction.
- on, in, or near the bottom
- unlike pelagic, benthic habitats involve characteristics of water column and underlying sediments.
SUB LITTORAL - CONTINENTAL SHELF
b). littoral - intertidal zone - depth depends on tidal range.
- transition zone
- narrow zone above normal high tide
- splash or spray zone
- temp. extremes and sunlight
- some inverts and algae thrive
- temp. extremes - receives full sunlight
- alternating cycles of flooding and dessication.
- productivity high on mud flats and tide masters.
- in tropics, mangrove forests
- organisms must be tolerate of extremes
- rapidly changing salinity, temp. and tides.
inner (above 150 m) and outer (150 - 200 m) zone based on depth of photic zoneSLOPE - BATHYBENTHIC- continental slope, rise and part of ocean floor to 4000m
- - sea grass, macro algae benthic - high productivity
- - serve as nursery for several organisms
- - include coral reef
- - communities, rich, varied
- - stable except where turbidity currents deposit sediments.
- - may be rich due to detritus rolling down slope
ABYSSAL ZONE -abyssal plains below 4000m - 6000m
Hadal zone (6000 - 10, 800 m) trench
- -soft bottom of ooze
- -food is organic detritus and bacteria (scare )