the ocean depths
Post on 08-Feb-2016
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THE OCEAN DEPTHS
THE OCEAN DEPTHS From 100-200 m (600 ft) to the
deepest part Mesopelagic (to depth of 3300 ft -
1000 m)Twilight
THE DEEP - Bathypelagic, Abyssopelagic & HadopelagicNo sunlight at all
THE MESOPELAGIC From 100-200 m to depth of 3300 ft
(1000 m) Not enough light for photosynthesis, no
primary productivity Enough light to see by – like twilight Chronically short of food High pressure
THE MESOPELAGIC - ADAPTATIONS
Small size Large mouths Hinged, extendable jaws Needle-like teeth Unspecialized diets Flabby watery flesh – no swim
bladder Large sensitive eyes Countershading & bioluminescence
THE MESOPELAGIC - ADAPTATIONS
THE DEEP From 1000 m – deepest trenches
No light Cold High pressure (up to 1000 atm) Lack of food Lack of mates
THE DEEP - ADAPTATIONS Small size (but larger than
mesopelagic) Black Small eyes Sluggish & sedentary Large mouths (consume prey larger
than themselves) Expandable stomachs Flabby watery flesh – no swim
bladder Hermaphroditism / Male parasitism /
Bioluminescence
THE DEEP- ADAPTATIONS
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Characteristics of the benthic zone:
- 90% of the organisms are found on the continental shelf, others are in the abyss
- deep sea benthhic fishes dark brown or black- meso- and deep pelagic zone 99% of the organisms are bioluminescent (produce light by chemical reaction)
- very stable environment - increases with depth
- lack of light is a major limiting factor - reducing food, predation and mating
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- oxygen is supplied from cold, saline waters of the poles
- biomass decreases with depth - this low population density is directly related to food scarcity
- communities entirely composed of consumers and scavengers
- producers are found only in photic zones; decomposers like bacteria are more common in mid-water mesopelagic zone
NOAA
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Hydro-Thermal Vent Communities
The exception in benthic communities’ producers are the chemosynthetic bacteria around hydrothermal vent.
NOAA
In 1977, scientists working in the DSV Alvin with project FAMOUS (Robert Ballard), discovered unique hydrothermal vent communities of previously unknown organisms.
Since then, vent communities have been found in all oceans at depths varying from 1 to 2 miles down.
Bacteria living near the vent use hydrogen sulfide dissolved in seawater to build organic molecules in a process called chemosynthesis.
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Animals clustered near the vents grow to huge sizes; can withstand temperature differences from 36o to 662o.
The community also has many suspension-feeders attached to the hard rock bottom which is unusual in the deep sea.
Geologist estimate that the vents probably last for 100 years;when supply of H2S is exhausted, the ecosystem dies.
In other areas, called Cold Seeps, also have chemosynthesis. Here methane and sulfide-rich fluids seep into the ocean floor where symbiotic bacteria use sulfur-oxidation for survival.
Cold Seeps are home to millions of benthic worms, crabs and mollusks.
NOAA
OCEAN FLOOR - SEDIMENTS
Continental shelf - terrigenous sediment derived from eroded continent
Ocean floor – biogenous sediment Derived from once living organisms
(plankton)
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20Radiolarians – equatorial regions
21Diatoms – polar regions
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