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Mollusca PhylumMollusca Phylum Octopuses, snails, squids and many others…Octopuses, snails, squids and many others…
GeneralGeneral
• Mollusca – from the Latin mollis – soft;
• Symmetry – bilateral (like humans);
• Taxonomy:- appeared 542 to 488.3 MYA;
- most closely related to arthropods, but more inferior than them;
- shared common ancestor with people around 550 MYA;
Unique characteristicsUnique characteristics• soft body usually protected by external
calcium-containing skeleton (shell);• 3 distinct body parts: head-foot (sensory &
motor organs) ; visceral mass (organs of digestion, excretion and reproduction); mantle (specialized tissue that secrets the shell and holds the body of the organism together) [+mantel cavity (houses the gills)];
• radula – toothed tongue; for digestion and sometimes for protection;
• at least two main nerve cords (3 in bivavlves);
ReproductionReproduction
• Most reproduce externally, but those that are more complex – internally;
• Hermaphrodites or dioecious (one individual is male, the other female);
• Releasing of eggs and external fertilization;
• eggs → larvae;
Locomotion & Nervous SystemLocomotion & Nervous System
– Locomotion - move with the help of a muscle on their down part of the body. This “foot” has a pair of statocysts and it secrets mucus.
– Nervous System – have two nervous cords – the visceral and the pedal ones.
RepresentativesRepresentatives
Blue Mussels (Mytilus edulis) – class Bivalvia;
Grove snail (Cepaea nemoralis) – class Gastropods;
Broadclub Cuttlefish (Sepia latimanus) - class Cephalopoda
Human InteractionsHuman Interactions • used for food;
• production of medicaments and drugs;
• pearls, shells – valuable items;
• sometimes they bite people and sometime the venom is so poisonous that the person dies;
Fun FactsFun Facts• • Octopi • Ø They have three hearts• Ø Their blood is light blue, just like aristocrats J• Ø They have 80 tentacles, each of which has 240 sucking cups (a total
of 1920) used for catching their victim. • Ø Just like sea stars, if their arm is cut, they can regenerate it
• • Slugs• Ø They have four noses• Ø A disgusting fact: sometimes right before mating slugs each other’s
slime
• • Snails• Ø Snails have the ability to slide on the edge of a blade and still not
get hurt• Ø If a person hums quietly to a snail for a little bit of time, the animal
will come out of its shell.
Works CitedWorks Cited• "Phylum Mollusca: Molluscs". 30.03.2010
http://infusion.allconet.org/webquest/PhylumMollusca.html• Driscoll, Barbara. "Mollusks [Mollusca]". Great Bay Estuary. 30.03.2010 http://
www.armofthesea.info/flora_fauna/ff_speciespp/moll.htm• "Body Symmetry of Mollusca". Forces of Nature. 30.03.2010
http://www.forces-of-nature.net/topics/molluscum/Body_Symmetry_Of_Mollusca.htm• "Mollusca Reproduction". Forces of Nature. 30.03.2010
http://www.forces-of-nature.net/topics/molluscum/Mollusca_Reproduction.htm• "Life Cycle of a Sail". Snail World. 30.03.2010 http://www.snail-world.com/Life-Cycle-
of-a-Snail.html• A.Pihlainen, "Octopus Fun Facts". 30.03.2010
http://ellerbruch.nmu.edu/classes/cs255w04/cs255students/apihlain/P5/P5.html• "Fun Facts on Slugs". Stumblerz. 30.03.2010 http://www.stumblerz.com/fun-facts-on-
slugs/• "Interesting Facts about Snails". Zephyrus. 30.03.2010
http://www.zephyrus.co.uk/interestingfactssnails.html• "Mollusca". Wikipedia® . 30.03.2010 <http://en.wikipedia.org/wiki/Mollusca>.