1. The Deep Ocean The deep oceans are divided into
various regions based on light,
plankton, and oxygen availability…
each of these regions supports
specific (and very different) types
of organisms…
Epipelagic
Mesopelagic
Bathypelagic
Abyssopelagic
Hadopelagic

2. The Deep Ocean
Many of the characteristics of deep ocean waters are a function of distance from surface;
however, remember that polar regions are a major source for these waters too…

3. The Deep Ocean
The movement of the colder polar waters to great depths is a part of a global pattern
of circulation known as the great ocean conveyor.
This circulation plays a central role in regulating the earth’s climate, and it
replenishes the deep seas with oxygen…

4. Organisms of the Deep Ocean The Mesopelagic
The mesopelagic contains large numbers of zooplankton (primarily krill, copepods,
and ostracods). There are also a number of deep water worms, squids,
and of course, fishes.
A major characteristic associated with many of these organisms is bioluminescence.
Most squids in these areas have photophores that contain bioluminescent symbiotic
bacteria and can help the animals give off light…

5. Organisms of the Deep Ocean The Mesopelagic
This bioluminescence allows for counter-illumination which helps with predator
(or prey) avoidance.

6. Organisms of the Deep Ocean The Mesopelagic
Furthermore, many of the fish, squid,
and arthropods have the ability to
regulate the amount of light given off
by their photophores…

7. Organisms of the Deep Ocean The Mesopelagic
Combination of life under very low light levels, as well as conditions where
bioluminescence is a major player, has evolutionarily selected for tubular eyes
with large retinal regions for many of the deep ocean organisms…

8. Organisms of the Deep Ocean The Mesopelagic
In addition to photophores, the different mesopelagic organisms will have varying
adaptations based on their ecology and “lifestyle”… Consider mesopelagic fishes
that may or may display daily vertical migration…
What would be possible advantages and disadvantages of each of these lifestyles?

9. Organisms of the Deep Ocean The Mesopelagic
Remember that the mesoplelagic is also
the zone of the oxygen minimum layer.
The effect of this change in the oxygen level
is evident in the morphology of the
different fishes…

10. Organisms of the Deep Ocean The Bathypelagic
The fishes of the bathypelagic look somewhat different…

11. Organisms of the Deep Ocean The Bathypelagic
Most deep ocean fishes will have large mouths… why do you think this is?

12. Organisms of the Deep Ocean The Bathypelagic

13. Organisms of the Deep Ocean The deep sea bottom fishes
In addition to being elongated,
deep-sea bottom fish tend to be
larger… this is part of a general
pattern referred to as deep-sea
gigantism.

14. Organisms of the Deep Ocean Review of the Fishes

15. Organisms of the Deep Ocean sex in the deep?
Many deep ocean organisms are hermaphroditic…
Others have separate sexes, but will use pheromones to attract mates…
Yet others will use patterns of bioluminescence for attraction of mates…
But stranger techniques do exist… consider the angler fish:

16. Organisms of the Deep Ocean Sources of food?… the surface?

17. Organisms of the Deep Ocean Sources of food?… hydrothermal vents?
Many hydrothermal vents in the deep ocean give off hydrogen sulfide. Certain bacteria
can use this chemical as a source of energy instead of the sun…
Entire communities are established based on direct or indirect feeding on the products
made by the chemoautotrophic bacteria…

18. Organisms of the Deep Ocean Sources of food?… hydrothermal vents?
The tube worm Riftia has symbiotic bacteria
that allow it to survive near hydorthermal
vents in the deep ocean…