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Great Barrier Reef - Australia

Living in association with the Great Barrier Reef is a multitude of higher animals which include shelled animals of the phylumMollusca (clams, cowries, mussels and sea-snails), radially symmetrical creatures of the phylumEchinodermata and includes sea urchins and starfish, elongated animals with segmented bodies occurring in the phylumsAnnelida and Arthropoda which includes bristle worms, shrimps and crabs as well as the vertebrates (phylumChordata) which includes cartilaginous and bony fishes and marine mammals such as dolphins and seals.

The giant clam Tridacna gigas and a Parrot Fish. The Giant Clam is the largest living bivalvemollusc. One of a number of large clam species native to the shallow coralreefs of the South Pacific and Indian oceans, they can weigh more than 400 pounds and measure as much as 1.5 meters across.

Sessile in adulthood, the creature's mantletissues act as a habitat for the symbiotic single-celled dinoflagellatealgae from which it gets it nutrition. By day, the clam spreads out its mantle tissue so that the algae receive the sunlight they need to photosynthesize.

Parrotfish are mostly tropical, perciform marine fish of the family Scaridae. Abundant on shallow reefs of the Atlantic, Indian and Pacific Oceans, the parrotfish family contains nine genera and about 80 species. Parrotfish are named for their oral dentition: their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot-like beak which is used to rasp algae from coral and other rocky substrates. Many species are also brightly coloured in shades of blue, green, red and yellow. Although they are considered to be herbivores, parrotfish eat a wide variety of organisms that live on coral reefs.

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