Chitons, sometimes called coat-of-mail shells, 

 are probably one of the most primitive types 

 of mollusc. They are sea slugs covered with 

 scaly plates arranged lil<e armor plating. 



Deceptively like its relative the giant clam 

 from this view, this species of a much 

 smaller clam (about six inches long) , 

 found on the Barrier Reef, displays a 

 brilliantly colored mantle. Like the oyster 

 and mussel, the clam is a bivalve mollusc. 



Among the larger crustaceans is this species 

 of hermit crab that lives on Australia's 

 Barrier Reef. Like other hermit crabs, this 

 one has found a home within the empty shell 

 of another animal (usually a gastropod). 



Among the smaller crustaceans are the 

 copepods, the main food of herring. Ranging 

 In size from a pinhead to a quarter of an 

 inch, copepods feed on the microscopic 

 diatoms found among the plankton population. 



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