Fish+and+their+Environment

__ **Fish** __

Over 1.5 million different species of fish and invertebrates have been discovered. Invertebrates, or animals without spines, play a major part in ocean life. Examples are jellyfish, crabs, sea anenomes and sea worms. Humans are almost identical to fish in our organs, like two chambered hearts and livers and bladders. Phytoplankton are the main source of food in the ocean. Bait fish eat the plankton and the larger fish eat the bait fish. The open ocean is one of the most desolate places in the ocean, but because of its size it is the most productive part of the ocean. Another part of the ocean that is smaller but more diverse and closely packed is the reef. The largest reef in the world is the great barrier reef. It stretches for over 1,600 miles and is comprised of hundreds of individual reefs and over 900 islands. Other than fishing, one of the reasons for dwindling fish populations are the introduction of alien species; species that were not originally found in the environment. These species are normally brought in by man. Examples are zebra mussels, and algae.



=Marine Mammals:= Other than fish, marine mammals are an important part in maintaining a balanced ecosystem. These include whales, dolphins, and dugongs. These species are becoming extinct because of loss of fish and habitats. Fish is the main source of food for dolphins and seals and because of commercial fishing and netting their food source is depleting quickly.

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