1. THE OCEAN DEPTHS

2. THE OCEAN DEPTHS From 100-200 m (600 ft) to the deepest part
Mesopelagic (to depth of 3300 ft m)
Twilight
THE DEEP - Bathypelagic, Abyssopelagic & Hadopelagic
No sunlight at all

3. 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

4. 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

5. THE MESOPELAGIC - ADAPTATIONS

6. THE DEEP From 1000 m – deepest trenches No light Cold
High pressure (up to 1000 atm)
Lack of food
Lack of mates

7. 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

8. THE DEEP- ADAPTATIONS

9. Characteristics of the benthic zone:
May 2008
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
Benthos - Combined

10. - oxygen is supplied from cold, saline waters of the poles
May 2008
- oxygen is supplied from cold, saline waters of the poles
- biomass decreases with depth - this low population density is directly related to food scarcity
NOAA
- 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
Benthos - Combined

11. Hydro-Thermal Vent Communities
May 2008
Hydro-Thermal Vent Communities
The exception in benthic communities’ producers are the chemosynthetic bacteria around hydrothermal vent.
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.
NOAA
Benthos - Combined

12. Animals clustered near the vents grow to huge sizes;
May 2008
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.
NOAA
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.
Benthos - Combined

13. OCEAN FLOOR - SEDIMENTS
Continental shelf - terrigenous sediment
derived from eroded continent
erosion, volcanic eruption, wind-blown dust
Ocean floor – biogenous sediment
Derived from once living organisms (plankton)
foraminifera, coccolithophores, radiolarians,diatoms

17. Foraminifera (amoeba-like organism), 5” spines

18. Foraminifera

19. Coccolithophore (planktonic algae)

20. Radiolarians – equatorial regions

21. Diatoms – polar regions