ZONE/ECOSYSTEMS OF THE OCEAN
INTERTIDAL ZONE
Location – On beach where ocean meets the sand, between high tide and low tide line on continental shelf.
Organisms – Sea grasses, periwinkle snails, herons, starfish, anemones, clams, crabs, snails, conchs, worms,
plankton. Simple organisms.
Adaptations – Some organisms have holdfasts which attach to rocks to keep the organism from washing away.
Some organisms release sticky glue to attach to rock and sand. Some organisms have suction cups to stay put.
Organisms must live in an area where the supply of water is uncertain; meaning they must be able to live in
water and out of water. For example, during low tide – they are exposed to sunlight and heat while at high tide
– they are pounded by waves. Organisms must also live in a zone that has high salt amounts.
Importance – none
NERITIC ZONE
Location – Expands from low tide line to continental rise. Spans from the low-tide line to the edge of the
continental shelf in oceans. Has a low water pressure, fairly stable temperature, and is a home to most of the
world's great fishing areas. This zone is particularly rich in living things.
Organisms – Bacteria, oysters, plankton, seaweed, sponges, coral, dolphins, fish, sea turtles.
Adaptations – None needed, since the living conditions are ideal.
Importance – World’s best fishing areas, lots of living things. Home to coral reefs. Great place for hobbies
(swimming, fishing, surfing, boating).
OCEANIC ZONE
Location – The open sea. Makes 65% of ocean water. Located from one neritic zone to the other, across the
ocean. Includes all three photic zones: the sunlight, twilight and midnight zone.
Organisms –
SUNLIGHT ZONE (top portion – sunlight, warm) – sharks, tuna, mackerel, jellyfish, sea turtles, seals, sea
lions, and sting rays.
TWILIGHT ZONE (middle portion – some sunlight, colder) – Octopus, squid, hatchet fish, viper fish no plants.
MIDNIGHT ZONE (bottom portion – no sunlight, coldest, highest pressure) – Organisms with no eyes, no
plants, worms.
Adaptations – Organisms live where there is no place to hide.
Sunlight zone – warm water, countershading (organisms are dark on top, light on bottom)
Twilight zone – Organisms live in water with high water pressure, cold temps and decreased sunlight. Some are
capable of making their own light (bioluminescence).
Midnight zone – no eyes and no bones.
Importance – A high variety of life. This zone makes up most of the ocean.
BENTHIC ZONE
Location – The entire ocean floor starting from low tide and going to the deepest parts.
Organisms – Many different types: organisms that crawl, shrimp, crabs, bacteria, sea urchins, worms, coral.
Not all live there full time; some can swim. The life in this zone is mostly made up of bottom dwellers which
get most of their food from dead and decaying organisms. Most of the organisms in the benthic zone are
scavengers, because they depend on dead flesh as their main food source.
Adaptations – Little food. Most of these organisms have adapted to feed on dead fish (decomposers). Some
organisms must live where there is little sunlight. Some have alternate sensory organs because of no light.
Some have the ability to eat chemicals (chemosynthesis).
Importance – Decomposing occurs there which keeps dead stuff from piling up. Home to creatures we haven’t
discovered, so important research is done there.
ESTUARIES
Location – Where freshwater (rivers) meets salty sea water (oceans). Located right before the ocean.
Organisms – Plankton, dolphins, manatees, seals, fish, worms, oysters, crabs, birds, plants (sea weed & marsh
grasses), cypress trees, swamp maple trees, black needle rush, swans, sea ducks, egrets, herons, bald eagle, glass
shrimp, blue crabs, glass shrimp.
Adaptations – Must be able to live with water that is rich in nutrients (nitrates, phosphates). Must be able to
live in brackish water.
Importance – Lots of different creatures. Betters the water quality – filters out dirt and pollution. Very
productive – lots of life. Home for life that needs fresh and salty water. People live their. Place for people to
do their hobbies (fishing, boating). Many types of animals spend some point in their life in estuaries.
CORAL REEF
Location – Warm shallow waters in neritic zone & benthic zone. They can be barrier reefs, fringing reefs, or
atolls. Can be found along continents.
Organisms – Coral, algae, fish, sponges, sea stars, sea urchins, octopus, stingrays, white-tipped sharks,
Adaptations – Some organisms use photosynthesis.
Importance – Give fish a home and place to lay eggs. Protect coasts from strong currents. Turns CO2 into
rock, which controls global warming.
HYDROTHERMAL VENTS
Location – On the sea floor on mid-ocean ridge where there is volcanic activity. Clustered in fields
underwater. On average, they are found a mile deep. The vents can be 6 ft in diameter. They are normally
found on mid-ocean ridges.
Organisms – Tube worms, mussels, shrimp, clams, snake-like fish, bacteria.
Adaptations – unsure why there are organisms down there. Able to live in hot and cold. Must be able to live
in darkness. Many organisms have no eyes.
Importance – Possible place where life on earth may have started. Some organisms can break down toxic
waste.