Phylum Mollusca

1. Phylum Mollusca http://www.palaeos.com/Invertebrates/Molluscs/Images/mollusc_classes.jpg

2. Triploblastic- 1st with coelom (small cavity space around various organs- for molluscs-heart and gonads) • Bilateral symmetry (3 body parts: head-foot, visceral mass, and mantle) • Visceral mass contains all organs • Mantle is outer layer and may secrete a shell • Mouth has radula structure which is a belt with rows of curved teeth on a tongue-like structure called an odontophore.

3. http://www.science.mcmaster.ca/Biology/Harbour/SPECIES/BIVALVIA/IMAGES/ORGAN1.GIFhttp://www.science.mcmaster.ca/Biology/Harbour/SPECIES/BIVALVIA/IMAGES/ORGAN1.GIF

4. Radula and odontophore http://upload.wikimedia.org/wikipedia/commons/thumb/4/45/Radula_diagram3.png/300px-Radula_diagram3.png

5. Molluscan shell loss and reduction… http://images.google.com/imgres?imgurl=http://www.andrewgray.com/essays/cepshell.gif&imgrefurl=http://www.andrewgray.com/essays/molluscs.htm&usg=__pHYWvKpK6tG9esL_b7xpQx8mQ8w=&h=234&w=312&sz=7&hl=en&start=2&um=1&tbnid=S2drmzyr1DDJZM:&tbnh=88&tbnw=117&prev=/images%3Fq%3Dmollusc%2Bloss%2Bof%2Bshell%26hl%3Den%26um%3D1

6. Class Gastropoda • Largest class of mollusks! (Snails, slugs, and limpets) • Undergo torsion in early development (body twisting 180°) • 3 advantages to torsion: • Head enters shell first to escape predators • Anterior opening allows clean water to enter mantle • Sensory organ around head help snail to be more sensitive to stimuli *some snail go through detorsion (twist 180- then untwist 90)

7. Most shells asymmetrical • Feed by scraping with radula • Cilia in digestive tract as well as on foot • Some gastropods have a siphon =rolled extension of the mantle • Respiration is by gills in aquatic snails, and by gas exchange through mantle in land snails • Open circulatory system with heart • Hydraulic skeleton of blood • Well developed sensory structures (tentacles with eyes) • Most marine snails dioecious, others monoecious • Eggs laid in external fertilization, deposited in moist environments

8. Limpets http://www.marietta.edu/~biol/biomes/images/shores/shield_limpet_6150.jpg http://www.guardian-series.co.uk/resources/images/231554/?type=display http://oceanexplorer.noaa.gov/explorations/04fire/logs/april14/media/limpet_eggs_600.jpg

9. Barnacles- NOT mollusks! http://www.mtkembla-e.schools.nsw.edu.au/gallery/galleryimages/barnacles.jpg http://www.restaurantwidow.com/images/2007/04/27/barnacles.jpg

10. Class Bivalvia • 2nd largest mollusk class (clams, oysters, mussels, scallops) • 2 halves = valves • Oldest part of shell = umbo (near anterior) • Hinges of protein to keep shell closed • Pearls made from secretions of mantle (best pearls come from pacific oysters) • Loss of head and radula • Folded Gills for resipration • Filter feed from water: cilia in bivalve moves food along food grooves toward mouth; labial palps sort food

11. Open circulatory system • Nervous system with ganglia (only some species have eyes- scallops) • Most dioecious, few monoecious • External fertilization- most brood young

12. http://oregonstate.edu/dept/ncs/photos/oysters.jpg http://www.pac.dfo-mpo.gc.ca/science/species-especes/shellfish-coquillages/geopath/Images/intro1.jpg http://blueoceannotes.files.wordpress.com/2009/08/oysters.jpg http://www.barrierreefaustralia.com/IMAGEGALLERY/giant-clam.jpg

13. http://community.adn.com/sites/community.adn.com/files/images/Weathervane%20scallops%20-%20ASMI.preview.jpghttp://community.adn.com/sites/community.adn.com/files/images/Weathervane%20scallops%20-%20ASMI.preview.jpg http://cookingoysters.co.uk/wp-admin/images/preparing%20mussels.jpg http://wednesdaychef.typepad.com/photos/uncategorized/mussels_1.jpg http://oceangrow.septentriones.com/data/upimages/scallop.jpg

14. Class Cephalopoda • Octopus, squid, cuttlefish, nautilus • Most complex of phylum mollusca • Foot modified into tentacles/arms and funnel for locomotion • Head is in line with visceral mass • Mantle has radial and circular muscles • Possess jaws and radula (octopus inject venom) • Locate prey by sight and capture with tentacles (mostly fish, crustaceans, and other invertebrates)

15. Nautilus is the only cephalopod with an external shell • Cuttlefish and squid have internal skeletons • Cuttlefish = Cuttlebone • Squid = Pen • The octopus has no shell • Closed circulatory system • Pigment cells (chromatophores) to change color • Complex nervous system- large brain/ganglia • Eyes similar to vertebrates

16. Ink glands behind anus • Dioecious • Reproduction by male placing spermatophoreinto female near oviduct; eggs are laid singly or in strings and usually attach to substrate.

17. Cuttlefish http://www.oceanfutures.org/spongebob/gallery/images/gallery_pim432c3.jpg http://fundiesvatheists.lefora.com/composition/attachment/c441ea1fa6c330e0c9bc72ff5c5e7d54/192970/ComCuttlefish9.jpg

18. Squid http://images.google.com/imgres?imgurl=http://neatorama.cachefly.net/images/2008-04/giant-squid.jpg&imgrefurl=http://www.neatorama.com/2008/04/30/colossal-squid-at-te-papa-museum-in-new-zealand/&usg=__1XokKm5sRqqkWnKCQx86OvA5f8I=&h=374&w=500&sz=46&hl=en&start=31&um=1&tbnid=qXUY7pVNM1cWgM:&tbnh=97&tbnw=130&prev=/images%3Fq%3Dsquid%26ndsp%3D20%26hl%3Den%26sa%3DN%26start%3D20%26um%3D1 http://images.google.com/imgres?imgurl=http://news.nationalgeographic.com/news/2007/02/images/070222-squid_big.jpg&imgrefurl=http://news.nationalgeographic.com/news/2007/02/070222-squid-pictures.html&usg=__b5FBOMpbizi4ZbuOxcWpzGr9uRI=&h=454&w=461&sz=59&hl=en&start=28&um=1&tbnid=1G9OtH5NzdUoQM:&tbnh=126&tbnw=128&prev=/images%3Fq%3Dsquid%26ndsp%3D20%26hl%3Den%26sa%3DN%26start%3D20%26um%3D1

19. Octopus http://www.smh.com.au/ffximage/2005/02/12/octopus_wideweb__430x308.jpg http://www.scuba-equipment-usa.com/marine/FEB04/images/Octopus_tetricus.jpg http://www.bbc.co.uk/devon/content/images/2007/12/06/blue_ringed_octopus_465x310.jpg http://media.smithsonianmag.com/images/deep4.jpg