mollusca aka the epitome of cool
DESCRIPTION
Mollusca aka the epitome of cool. Briana O’Leary Raissa Largman. http://www.greenexpander.com/wp-content/uploads/2007/12/octopus.jpg. Animals. Four major classes: 1. Polyplacophora: chitons 2. Gastropodia: snails 3. Bivalvia: clams, mussels, scallops, oysters - PowerPoint PPT PresentationTRANSCRIPT
Molluscaaka the epitome of cool
Briana O’LearyRaissa Largman
http://www.greenexpander.com/wp-content/uploads/2007/12/octopus.jpg
Animals
Four major classes: 1. Polyplacophora: chitons 2. Gastropodia: snails 3. Bivalvia: clams, mussels, scallops, oysters 4. Cephalopoda: squids, octopuses, cuttlefish, chambered nautiluses
Briana
Polypacophora
http://reefguide.org/pix/thumb2/chiton4.jpg
Chiton: marine, shell with 8 plates, foot used for locomotion, radula, no head.
Raissa
Gastropoda
• http://photography.nationalgeographic.com/staticfiles/NGS/Shared/StaticFiles/Photography/Images/Content/green-snail-laman-400957-sw.jpg
Characteristics: Marine, freshwater or terrestrialAsymmetrical BodyUsually has a coiled shellShell reduced or absent in someFoot for locomotionRadula
Briana
Bivalvia
Marine and FreshwaterFlattened shell with two valvesHead reducedPaired gillsNo radulaMost are suspension feedersMantle forms siphons
http://www.barrierreefaustralia.com/IMAGEGALLERY/giant-clam.jpgRaissa
Cephalopoda
MarineGrasping tentaclesUsually has suckersCan have shell/radulaLocomotion through
jet propulsion
http://fractalontology.files.wordpress.com/2008/03/nautilus.jpg
Briana
Basic Body PlanBody Cavity: Present. Fluid filled coelom.
http://www.bio.miami.edu/dana/pix/ham.jpg
-Muscular foot-Visceral mass- mantle (fold of tissue over visceral mass)
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Body Symmetry: Varies. Gastropods: Asymmetrical
Other classes are bilaterally symmetrical.
http://open.live.bbc.co.uk/dynamic_images/naturelibrary_640_credits/downloads.bbc.co.uk/earth/naturelibrary/assets/o/oc/octopus/octopus_1.jpg
http://www.bio.miami.edu/dana/pix/bodysymmetry.jpg Briana
Nervous System
Nervous System: Present Nerve ring around the esophagus from which
nerve cords extend Cephalopods: Highly complex system with brain. Estimated that an octopus has the same intelligence of a house cat.
Raissa
Circulatory System
Open system- heart pumps hemolymph through arteries into body spaces (constantly bathed)
except in cephalopods- have closed circulatory systems
http://www.cartage.org.lb/en/themes/sciences/lifescience/GeneralBiology/Physiology/CirculatorySystem/CirculatorySystem/TypesCirculatory/circsys_2.gif
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Digestive System
Complete: mouth, anus complex stomachMany use radula to scrape up food, suspension feeders (many bivalves) collect food particles from water that passes over gills
http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-21-ClamAnatomy-L.jpg
Raissa
Excretory System
Present:Nephridia: tubular structures that collect fluids
and exchanges salts with body tissues.
http://www.sharky1.com/Images/marine/mini%20cuttlefish.jpgBriana
Locomotion/Musculature
Varies Muscular foot (Chitons
and Gastropods) Jet propulsion
(Cephalopods) Lateral fins: (Cuttlefish)
Bivalvia: Mainly sedentary http://www.pc.gc.ca/~/media/pn-np/bc/pacificrim/e-f/E-17_RAZOR_CLAM.ashx
http://palaeo.gly.bris.ac.uk/Palaeofiles/Fossilgroups/Cephalopoda/Sub-squid.JPG
Raissa
Skeletal Type
Soft bodied but most have a hard shell made of calcium carbonate.
In some, the shell is absent or internalized.
http://bama.ua.edu/~musselp/graphics/presentations/shell_show_2004_1.jpg
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Sensory Structures/FeaturesVaries considerably between classes. Cephalopods have complex sensory capabilities. Giant Squids: Largest eyes in the animal kingdom Bivalves: Small eyes and sensory tentacles Gastropods: Eyes at the tips of tentacles
http://www.nefsc.noaa.gov/press_release/2008/SciSpot/ss0810/T%20megalops%202038%20copy.jpg
http://www.genomicon.com/wp-content/uploads/2009/04/snaileye.jpg
http://www.augsburg.edu/home/biology/photoofmonth/scallopeyes-wide-big.jpg
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Reproduction
Mainly separate sexes with gonads: ovaries or testes.
Many snails (gastropods) are hermaphrodites. Life cycle of many marine mollusks includes a
ciliated larval stage: trochophore
http://www.nicertutor.com/doc/class/bio1903/Locked/media/ch32/32_13Trochophore.jpg
Briana
Gas ExchangeMarine mollusks have gills. Water enters mantle cavity through a
siphon, passes over gills, and then exits mantle cavity through another siphon.
Terrestrial snails: lining of the mantle = lung
http://kentsimmons.uwinnipeg.ca/16cm05/1116/33-21-ClamAnatomy-L.jpg
Raissa
Other Unique FeaturesThere are twice as many species belonging to the phylum
Mollusca than there are vertebrates.
Gastropods: Torsion – Developing embryo’s visceral mass rotates up to 180 degrees causing its anus and mantle cavity to wind up above its head.
http://www.palaeos.com/Invertebrates/Molluscs/Gastropoda/Images/torsion.gif
Briana
QUIZ
1. Name the four classes that comprise Mollusca.
2. What type of excretory organ is present in Mollusca?
A. Kidneys B. Nephridia C. No excretory organ D. Malpighian tubules
3. What class has a closed circulatory system? A. Gastropods B. Bivalves C. Polyplacophora D. Cephalopods
4. Shells of Mollusks are A.AbsentB. InternalizedC. PresentD.All of the above
http://www.fish.govt.nz/NR/rdonlyres/836B96BF-12FE-417D-AB49-4B46B2DB8729/0/ColossalSquid.jpg