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>.