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Oceanic Zones 1

Page history last edited by Sebastian B 11 years ago


Bathyal Zone







Coral Reef: 

            Coral reefs are composed of coral polyps, a small animal in the phylum Cnidaria, which is related to jellyfish.  Coral polyps will release eggs and sperm, and these produce a larva called a planula.  This larva will float through the ocean until it finds a hard surface where it can take hold.  It then uses carbon dioxide and calcium in the water to form a calcium carbonate shell.  Coral reefs are built up from many layers of dead coral shells.  Tan parts of the reef are dead, while the living parts are colorful. Coral reefs only grow about half an inch a year, but they can become extremely large.  Australia’s Great Barrier Reef in Australia is about 100 miles long.

            Coral reefs prefer to grow in a tropical ocean, close to shore.  They also prefer to be close to the surface, in sunny, shallow, clear water.  Also, the water must be salty.  They prefer temperatures of 25-31 degrees Celsius and a salinity of 34-37 parts per thousand.

            The three main types of coral reefs include the fringing reef, which is a continuous platform extending from shore.  The second is the barrier reef, which is separated from shore by a wide, deep lagoon.  These usually occur when a reef grows upward to remain near sunlight after a rise in sea levels.  The last type of reef is the atoll, a circular reef surrounding a lagoon.  These develop when an island surrounded by barrier reefs subsides underwater, or when sea levels rise above the island and the reefs continue to grow upward.

            Coral get energy and oxygen through a symbiotic relationship with an algae called zooxanthellae, which grows within the shell of a coral polyp and produces energy through photosynthesis.  The coral helps provide shelter for the algae.

            Coral reefs have many benefits.  They provide habitat for many types of fish, and products from coral reefs feed 30-40 million people per year.  Coral reefs also absorb carbon dioxide in the water and protect the shoreline from winds and ocean currents.

            Coral reefs are threatened by global warming, which kills reefs due to bleaching, or killing their algae, as well as covering them under rising seas.  Also, some fishermen use poison or explosives to stun fish so that they are easier to catch, which causes damage to the reefs.


Estuary: An estuary is a body of water along the coast that is partially enclosed. It is where freshwater from rivers and streams and saltwater meets.. Estuaries are transition areas. They are influenced by the ocean tides but are safe from waves and storms. Other names for estuaries are bays, lagoons, harbors, and sounds. They provide vast amounts of organic matter. They are shallow open waters, marshes, swamps, sandy beaches, mud and sand flats, rocky shores, and oyster reefs in estuaries. The animals include birds, fish, crabs, lobsters, marine mammals, clams, worms, and reptiles.


Intertidal Zone:  The Intertidal Zone is the area on the coast that is covered in water at high tide, and is left uncovered at low tide.  There are three sub zones in the Intertidal zone: the High tide, Middle tide, and Low tide zones.  The High tide zone is extremely salty (due to the water evaporating and leaving behind the salt) and can have vast differences in temperature.  Few organisms are able to survive in this area.  Organisms that carry their homes on their backs, such as the crab, are able to live in this area.  Vegetation is limited in this area to plants such as algae.  The Middle tide zone is not as salty as the high tide zone because water washes over the surface more often, so it doesn’t give the water time to evaporate.  Because this zone has a lower salinity, more complex organisms are able to live here. The final zone, the Low tide zone, is almost always covered with water. The only time this land is exposed is when there is an unusually low tide.  More complex organisms live in this area than any other intertidal zone.  Brown Seaweed and Sea Cucumbers grow in this area.


Coastal Zone: The Coastal Zone is the warm, shallow water that extends from the high-tide mark on land to the continental shelf, which is the submerged part of continents. This zone contains ninety percent of all marine species. Some animals found in this zone include stingrays, hammerhead sharks, seahorses, eels, angelfish, sea cucumbers, finch, and sea turtles. Plants include mangroves, sedge, salt bush, and Galapagos carpetweed. Here, organisms thrive off an ample supply of sunlight and nutrients that flow from the land and are distributed by wind and ocean currents. The Coastal Zone faces numerous interactions with the land, thus human activities easily affect the area. They are the site of most large commercial marine fisheries.

Types of Coastal Zones:

  • Estuaries: Enclosed areas of coastal water where seawater mixes with freshwater. These are ectones between the ocean and freshwater land.
  • Coastal Wetlands: Land areas covered with water all or part of the year.
  • Estuaries and Coastal Wetlands include river mouths, inlets, bays, sounds, mangrove forest swamps, and salt marshes

Characteristics of Coastal Zones:

Temperature and salinity levels vary due to the daily rhythms of the tides, seasonal variations in the flow of freshwater, unpredictable flows of freshwater after heavy rains, and unpredictable flows of salt water due to hurricanes and typhoons.




Rocky Shore



  • By its name, it is easy to tell that this biome is a rocky section of an ocean shore
  • It is located at many coastlines around the world
  • Being a marine biome, it is not affected much by the climate or rainfall which means that it can be in many different places
  • Unlike sandy shores, its rocks provide a permanent habitat for certain types of organisms
  • A rocky shore will not go on for long however, it is often mixed with sandy shores



·         In the zone between high tide and low tide, the rocks are mostly covered with barnacles

·         They are competitive in this environment because they can hold onto the rock face and are resistant to desiccation (state of extreme dryness)

·         They come in different sizes that compete with each other which usually ends in the larger ones surviving because they have longer legs that can extend to filter out microscopic plants and animals known as plankton

·         Another major competitor are black mussels that use byssal threads to attach to the rocks

·         The main plant life are multicellular algae known as seaweed





Abyssal zone(salt water): The Abyssal zone is the deepest layer in water. This layer stays dark all the time, never receiving daylight. Some of its inhabitants are the Black Swallower, the Tripod fish, and the Deep Angler Fish; these creatures are able to withstand incredible pressures at the bottom of the ocean. The zone averages about 2-3 degrees Celcius.  



Barrier Islands, also know as barrier spits, can be found on coastlines all over the world. They are most noticeable along the eastern coast of North America, where they extend from New England down the Atlantic coast, around the Gulf of Mexico and south of Mexico. Barrier Islands are long, narrow, offshore deposits of sand or sediments that parallel the coast line. Barrier Islands serve two main functions. First, they protect the coastlines from severe storm damage and second, they harbor severe habitats that are refuges for wildlife.  


Euphotic: This zone is also called the photic zone. Here, sufficient light is available for producers to undergo photosynthesis.  Phytoplankton provide energy through photosynthesis, which the rest of the food system is dependent upon. Algae, fish, tuna, dolphins, seals, and sea lions abide. This is the only zone where photosynthesis can take place, so competition for space among different species dependent on light can be a challenge. 





Mangal Zone


Mangrove-     is a plant that has adapted to an intertidal zone by developing physiological adaptations to overcome problems of anoxia, high salinity, and frequent flooding.

                        Anoxia- lack of oxygen

                        Salinity- salt concentration


Mangal-          the region or are where mangroves live and thrive


Mangroves protect the coast from:


                        -surge storms



            -wave energy is generally low where mangroves live

-erosion still occurs on the outer sides of bends in river channels that wind through mangroves

Intricate root systems provide homes for organisms such as:





                        -bryozoans (similar to coral)


                        -mud lobsters

                        -mangrove crabs


There are 110 known species of mangroves. Of these, only about 54 species in 20 genera from 16 families are “true mangroves”. This means that those species occur almost exclusively in mangrove habitats and rarely anywhere else.


Adaptations to low oxygen:

            -Red mangroves prop themselves up on roots that act as “stilts”

                        -take in air through pores in the bark.

            - Black mangroves create pneumatophores

-Pneumatophores- specialized root-like structures which stick up out of the soil like straws for breathing.

                        -both the stilts and the straws are covered in lenticels, the air pores.

                                    -Pneumatophores typically grow between 30cm to over 3 meters

                                    -there are 4 types of pneumatophores:






Comments (1)

Matt F said

at 9:38 pm on Mar 9, 2009

I tried to put pictures on the Rocky Shore but they didn't show up.

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