The ocean's ecosystem is unique among aquatic ecosystems because the amount of salt water required to maintain and balance the landscape is greater than the amount of fresh water needed. Ocean ecosystems have distinct characteristics and contain various life forms found only in this environment. While ocean ecosystems do have much in common with other aquatic ecosystems, such as freshwater lakes, rivers or estuaries, they are unique in many ways, especially because of the high salt water levels.

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Ocean ecosystems are comprised of a variety of unique life forms.

Salt Water

Butterfly fish
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Butterfly fish swim over reef

Ocean ecosystems are predominantly salt water ecosystems. While there may be some fresh water present in the environment, salt water is the primary type of water necessary to sustain all of the life forms present in the ecosystem.

Ocean Location

Orca
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Two killer whales swim past an iceberg in the Arctic Ocean

Ocean ecosystems are found only in the five oceans. These include the Atlantic, Arctic, Pacific, Southern and the Indian oceans.

Salt Water Life Forms

Rainbow or Salmon trout  (Oncorhynchus mykiss)
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Trout swimming in fresh water

All of the life forms within an ocean ecosystem are creatures that have adapted to living in a salt water environment. Fresh water life forms, such as fresh water fish, that accidentally enter an ocean ecosystem will typically be unable to survive in this environment. Countless life forms exist in a given ocean ecosystem. Over 500,000 separate species are contained in coral reef ocean ecosystems worldwide, giving this particular ecosystem more species per square meter than any other ecosystem, according to the Smithsonian Institute.

Balanced Food Chain

Whale underwater
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Blue whale below the ocean's surface

The ocean ecosystems contain a unique and multi-part food chain that is comprised of thousands of creatures. Creatures of all sizes are found within the ocean ecosystem. Small fish and crustaceans typically feed on ocean plants, plankton and corals. Species such as the blue whale-the largest creature on earth-and other large creatures feed on the smaller creatures. Ocean tides help to form the sand bars and reefs where the ocean plants grow. The smaller ocean species need these plants to live and the larger species need the smaller species to live. Each facet of the ecosystem works together in a delicate balance to achieve and maintain the food chain.