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Phylum Mollusca

Phylum Mollusca. Chapter 13: Phylum Mollusca pp. 329-334. Biology fun facts of the day:. Experts claim that about 1,000 oysters must be opened in order to find one usable pearl!. Biology fun facts of the day:.

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Phylum Mollusca

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  1. Phylum Mollusca Chapter 13: Phylum Mollusca pp. 329-334

  2. Biology fun facts of the day: Experts claim that about 1,000 oysters must be opened in order to find one usable pearl!

  3. Biology fun facts of the day: The common garden snail, Helix aspersa, can travel about 2 feet in 3 minutes. At that rate, it would travel 1 mile in 5.5 days. (Now you know where the term ‘snail mail’ comes from!)

  4. Biology fun facts of the day: When we hold a large seashell up to our ear, you can hear what sounds like waves because the shell echoes all the sounds around you. If you could listen to a shell in a completely soundproof room, you would hear nothing at all!

  5. Biology fun facts of the day: Many land snails can lift 10 times their own weight up a vertical surface. (If you were this strong, and you weighed 30 kg (about 70 lb), you could carry 300 kg (almost 700 pounds!!!) straight up a wall!

  6. Introduction to Molluscs Molluscs represent the second largest animal phylum, following the arthropods = Old Phylum (500 million years, approx.) 80,000 – 100,000 existing species (estimate) Most species are free-living Inhabit a variety of marine, aquatic & terrestrial habitats Important ecological roles with regards to nutrient recycling; bivalves clean and recycle sediments Empty shells provide habitat for other invertebrates

  7. Where do Molluscs fit in?

  8. Introduction to Molluscs • Phylum Mollusca – Latin molluscus= “soft” • Protostomes • Bilateral symmetry; eucoelomates • 3 cell layers (ectoderm, endoderm, mesoderm) • Have a coelom(but often reduced to a cavity that surrounds only the heart) • Have trochophore larvae (free-swimming ciliated larva) • Similar larvae in annelids  likely share a common ancestor

  9. Introduction to Molluscs Molluscs all share similar developmental patterns and a common body plan: • Foot (muscle; function varies) • Shell (protection; made of CaCO3) • Mantle (produces the shell) • Visceral mass (contains internal organs) Diagrams of snail, clam, and squid p. 300

  10. Classes of Molluscs 1) Class Bivalvia • 2 hinged shells • No head or eyes • Gills; live in water Example members: clams, oysters, scallops 2) Class Gastropoda • One shell • Some are terrestrial Example members: snails, slugs, nudibranchs

  11. Classes of Molluscs 3) Class Cephalopoda • Fast-moving predators • Foot is modified into tentacles • Well-developed nervous system • Some can use camouflage and jet propulsion (e.g. octopus) when they feel threatened Example members: octopus, squid, nautilus, cuttlefish Nautilus Squid Octopus

  12. Squid are the largest Cephalopods

  13. Colour and Morphology Changes = Camouflage

  14. Form and Function of Molluscs Molluscs vary a lot  clam = representative mollusk Digestive system: • Complete digestive tract (mouth  anus) • Mouth, esophagus, stomach, intestine, anus • Have a radula (scraping/drilling organ) or a beak (cephalopods) • Bivalves trap food in their gills – no radula e.g. Gastropod

  15. Form and Function of Molluscs • Respiratory system: • Aquatic mollusks have gills • Terrestrial mollusks have a highly folded mantle for O2/CO2 exchange (must stay moist) • *A clam has incurrent and excurrent siphons  sea water passes through; location of gas exchange

  16. Circulatory system: • Open circulatory system – the heart pumps blood through open spaces called sinuses instead of through blood vessels Excretory system: • Nephridia (primitive kidneys) remove metabolic waste (nitrogen-containing wastes like NH3) • Digestive wastes go out anus

  17. Nervous system: • Bivalves – reduced nervous system; no head • Gastropods – fairly basic • Cephalopods – very well developed • Good vision, small ganglia near mouth, statocysts (balance), simple chemical and touch receptors • Good dexterity and memory – theycan learn!

  18. Musculoskeletal system: • Muscular foot for movement • Bivalves – “two shell”; foot pulls animal forward, and can be sucked back in (for protection) • Gastropods – “stomach foot”; they slide forward on broad ventral foot (use muscus) • Cephalopods – “head foot”; foot has been modified into many tentacles with suction cups e.g. Gastropod

  19. Reproduction: • Some Monoecious(have both sex organs, capable of producing both sperm and eggs) • Others are Dioecious (either male or female gonads, can produce one type of gamete only) • Separate sexes (usually) • External fertilization (broadcast method) in bivalves/marine gastropods)  the female traps sperm • Internal fertilization in cephalopods/terrestrial gastropods

  20. Ecology of Molluscs • Bivalves used to check pollution levels – “environmental monitors” • Range of lifestyles: predators, scavengers, filter feeders, etc. • Crop damage – slugs, snails on land • Ship damage – shipworms in water • Food source for humans: clams, oysters, mussels, etc. • Humans can get poisoned by eating mollusks contaminated with toxic protists  cause “red tide”

  21. Molluscs Movie!

  22. Mollusc (5-7-5) Haiku: Slow, slick, sliding slug Terrestrial explorer No protective shield Create your own mollusc haiku in 5-7-5 format!

  23. Works Cited Images taken from the following sources: http://other95.blogspot.com/2007/10/circus-of-spineless-26-like-being-home.html http://offthemark.com/search-results/key/mollusk/ http://kevinmainjewelry.blogspot.com/2010/06/pearl-fun-facts-and-care-tips.html http://seashellvilla.com/advertise_here.html http://www.zazzle.com/snail_mail_postcard-239469706654312651 http://bio1151b.nicerweb.com/Locked/media/ch32/trochophore.html http://www.education.com/study-help/article/biology-help-mollusks-clam-up-would-ya/

  24. Works Cited http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCESearchMedia&Params=A1&MediaId=385 http://perfectgardeningtips.com/category/plants/pest-control/ http://www.apartmenttherapy.com/sf/insects-pests/slugs-082896 http://birdhouse.org/blog/2008/05/16/nudibranchs/ http://www.zazzle.com/i_squid_cephalopods_tshirt-235319078835508111 https://www.mentalfloss.com/blogs/archives/58856 http://radio-weblogs.com/0105910/2004/01/10.html http://ihatetheocean.blogspot.com/2010/08/august-6-2010-nautilus.html http://zollberg.co.cc/bivalve.html

  25. Works Cited http://js082.k12.sd.us/My_Classes/Advanced_Biology/Ch_25/Clam%20Dissection/Clam_Dissection.htm http://www.sciencewithme.com/learn-about-mollusks/ http://www.bio.miami.edu/dana/106/106F06_12.html http://nashzoology.ning.com/forum/topics/mollusk-classification-choose?commentId=2223964%3AComment%3A10692&xg_source=activity http://sharon-taxonomy2009-p3.wikispaces.com/Mollusca http://www.lifeinfreshwater.org.uk/Web%20pages/ponds/Pollution.htm http://www.nero.noaa.gov/nero/hotnews/redtide/ http://www.sheppardsoftware.com/content/animals/profile_mollusks.htm

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