• Mollusks is the group that includes Shellfish (Bivalves), Snails (Gastropods), Octopuses (Cephalopods), and their relatives.
• All mollusks have a mantle, a fold of skin that covers part of the body like a blanket.
• The mantle secrets the shell, made of calcium and carbonate. Most mollusks have a shell or at least a layer of scales made in this way.
• In some mollusks the mantle forms a tube called the siphon, which they use to pump water, containing nutrients, inside their body.
• Almost all mollusks have ctenidia, which are like a primitive version of fish gills, and look like tentacles.
• The only exceptions are terrestrial snails, in which the mantle has developed a chamber similar to a lung.
• Many mollusks have a foot. Shellfish-like mollusks use it for digging or scavenging, while snails like to use it for moving from place to place.
• Many mollusks a tongue covered in teeth called Radula, to rasp off their food.
• The internal pressure of water supports mollusks’ bodies. Controlling this water, they can expand and contract their bodies or part of them.

	Chitons; photo by Ryan Wick cc-by	Clams; photo by Scott*eric cc-by

Sources:

-The Tree of Life - www.tolweb.org:
-The Variety of Life, Colin Tudge, 2000

Citation: García, A.I. 2015. The Tree Of Nature (Online) at http://thetreeofnature.com

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