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Oceanic Zones Notes
Overview
 More than 250,000 identified marine species
 Most live in sunlit surface seawater
 Species success depends on ability to:
 Find food
 Avoid predation
 Reproduce
 Cope with physical barriers to movement
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Plankton and Zooplankton
Nekton
 Independent
swimmers; can
migrate
 Most adult fish
and squid
 Marine mammals
 Marine reptiles
Benthos
 Most abundant in shallower water.
 Three types:
 Epifauna live on or near the bottom of the sea floor.

Oysters, sponges, sea squirts, sea stars, barnacles
 Infauna live buried in sediments.

Worms, clams
 Nektobenthos swim or crawl through water above seafloor.
 Cephlapods, turtles & other reptiles, marine mammals
Marine Division by Light
 Photic Zone (photo- means light):
the sunlit layer of the ocean’s surface that extends to a depth of
600 meters (2000 feet)
a)
a)
Euphotic Zone- upper part of photic zone,
lots of light for plant production to support photosynthesis
Disphotic Zone- lower part of photic zone,
animals can see but there is insufficient light for photosynthesis
 Aphotic Zone (a- means without):
the deepest and largest region
of the open ocean that extends
to the ocean bottom
Photic Zone
 More than 90% of all marine life lives in the photic zone
of the ocean
Photic Zone
Euphotic Zone
 Euphotic Zone: Top layer of the ocean
Photic Zone
Euphotic Zone
Disphotic Zone
 Disphotic Zone: Only a small amount of light penetrates the water. (Plants do
not grow here due to the insufficient amount of light.)
Photic Zone
Euphotic Zone
Disphotic Zone
 Aphotic Zone: Entirely dark; no light
Marine Division by Location
 Pelagic Zone - open water, divided into Neritic
Zone (near shore over continental shelf) and
Oceanic Zone (deep water beyond the continental
shelf)
 Benthic Zone -division of ocean bottom
pelagic zone
 Divided into two zones:
benthic zone
Pelagic Environments
 Epipelagic-
photic
zone/sunlight zone
 Mesopelagic-
disphotic
zone/twilight zone
 Bathypelagic-
aphotic
zone/midnight zone
 Abyssopelagic-
abyssal zone/abyss
 Hadalpelagic-
deep trench/hadal
Benthic Environments
 Supralittoral
 Subneritic
 Littoral
 Sublittoral
 Inner
 Outer
 Suboceanic
 Bathyal
 Abyssal
 Hadal
Supralittoral Zone- the splash zone,
right above the high intertidal zone
Subneritic:
Littoral Zone- where the coast is
covered and uncovered by tidal action
Sublittoral Zone- past the
littoral, divided into:
 Inner Sublittoral (ocean
bottom near the shore)
 Outer Sublittoral (ocean
bottom out to the edge of the
continental shelf)
Suboceanic:
 Bathyal Zone- bottom that covers the areas on
the continental slopes down to great depths
 Abyssal Zone- the dark, lower regions which
includes the deepest sea floor but not the trenches
 Hadal Zone- deepest of all the sea floor, trench
walls and bottom of trenches