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More About Molluscs - Misc. ...
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The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. These range from tiny snails and clams to the octopus and squid (which are considered the most intelligent invertebrates). The giant squid is the largest invertebrate, and, except for their larvae and some recently captured juveniles, has never been observed alive, although the Colossal Squid is likely to be even larger.
Mollusks are triploblastic protostomes. The principal body cavity is a blood-filled hemocoel, with an actual coelom present but reduced to vestiges around the hearts, gonads, and metanephridia (kidney-like organs). The body is divided into a head, often with eyes or tentacles, a muscular foot and a visceral mass housing the organs. Covering the body is a thick sheet called the mantle, which in most forms secretes a calcareous shell.
Mollusks have a mantle, which is a shell-like outer cover, and a muscular foot that is used for motion. Many mollusks have their mantle produce a calcium carbonate external shell and their gill extracts oxygen from the water and disposes waste. All species of the phylum Mollusca have a complete digestive tract that starts from the mouth to the anus. Many have a radula, mostly composed of chitin, in the mouth, which allows then to scrape food from the surface by sliding back and forth. Mollusks also have a coelom, made from cell masses, where all organs are suspended. Unlike Coelomates, mollusks lack body segmentation.
Development passes through one or two trocophore stages, one of which (the veliger) is unique to the group. These suggest a close relationship between the mollusks and various other protostomes, notably the Annelids. Mollusk fossils are some of the best known and are found from the Cambrian onwards.
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Taxonmony
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Phylum: Mollusca
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Source: Wikipedia Read more about Molluscs - Misc.
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INFO LINKS
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Gastropod
Jacksonville Shell Club
Gastropods Read More
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nautilus
BBCi
General information. Good for kids Read More
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Golden Cowrie
National Geographic
Golden Cowrie fact sheet and pictures Read More
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Nudibranch
National Geographic
Nudibranch fact sheet and pictures Read More
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Cuttlefish
Oceanes - the holiday designer
Brief description and categorized information about Cuttlefish Read More
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Nautilus
Oceanes - the holiday designer
Brief description and categorized information about Nautilus Read More
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Nudibranch
Oceanes - the holiday designer
Brief description and categorized information about Nudibranch Read More
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Nudibranch
Jeff's Nudibranch Site and Coral Reef Gallery
Spectacular pictures of Nudibranches Read More
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Cuttlefish
Unique Australian Animals
Categorized information on Cuttlefish including description, habitat, feeding, etc. Has nice pictures, too. Read More
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Chambered Nautilus
National Zoo
Chambered Nautilus fact sheet Read More
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Cephalopod
National Zoo
Cephalopod fact sheet Read More
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Gastropod
Natural History Museum - Archerd Shell Collection
Image gallery of Gastropods Read More
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Chiton
Natural History Museum - Archerd Shell Collection
Image gallery of Chitons Read More
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Tusk Shell
Natural History Museum - Archerd Shell Collection
Image gallery of Tusk Shells Read More
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Cephalopod
Natural History Museum - Archerd Shell Collection
Image gallery of Cephalopods Read More
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Chiton
A Beginner's Introduction to Molluscs
Kid friendly article about chitons Read More
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