Biol 11 Lesson 1 Mar 2 - Ch. 27 Mollusca


Published on

Biology 11
Animal Biology unit - Invertebrates
Miller, K.R. & Levine, J. (2000). Biology (5th ed.). New Jersey: Prentice Hall.
Ch. 27: Mollusks and Annelids
pp. 584-593

Published in: Education
1 Comment
  • it is very useful to me
    Are you sure you want to  Yes  No
    Your message goes here
  • Be the first to like this

No Downloads
Total views
On SlideShare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Biol 11 Lesson 1 Mar 2 - Ch. 27 Mollusca

  1. 1. Homework from last class: <ul><li>Read Ch. 27-1 Mollusks </li></ul><ul><li>Read over class notes and check out the class blog: </li></ul>
  2. 2. Phylum Mollusca: Mollusks Chapter 27: Mollusks and Annelids pp. 584-593
  3. 4. <ul><li>Biology fun facts of the day: </li></ul>Experts claim that about 1,000 oysters must be opened in order to find one usable pearl!
  4. 5. <ul><li>Biology fun facts of the day: </li></ul>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!)
  5. 6. <ul><li>Biology fun facts of the day: </li></ul>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!
  6. 7. <ul><li>Biology fun facts of the day: </li></ul>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!
  7. 8. Introduction to Mollusks <ul><li>Phylum Mollusca – Latin molluscus = “soft” </li></ul><ul><li>Bilateral symmetry </li></ul><ul><li>3 cell layers (ectoderm, endoderm, mesoderm) </li></ul><ul><li>Have a coelom (but often reduced to a cavity that surrounds only the heart) </li></ul><ul><li>Have trochophore larvae (free-swimming ciliated larva) </li></ul><ul><ul><li>Similar larvae in annelids  </li></ul></ul><ul><ul><li>likely share a common ancestor </li></ul></ul>
  8. 9. Introduction to Mollusks <ul><li>Mollusks all share similar developmental patterns and a common body plan: </li></ul><ul><li>Foot (muscle; function varies) </li></ul><ul><li>Shell (protection; made of CaCO 3 ) </li></ul><ul><li>Mantle (produces the shell) </li></ul><ul><li>Visceral mass (contains internal organs) </li></ul>Diagrams of snail, clam, and squid p. 586
  9. 10. Classes of Mollusks <ul><li>1) Class Bivalvia </li></ul><ul><ul><li>2 hinged shells </li></ul></ul><ul><ul><li>No head or eyes </li></ul></ul><ul><ul><li>Gills; live in water </li></ul></ul><ul><ul><li>Example members: clams, oysters, scallops </li></ul></ul><ul><ul><li>2) Class Gastropoda </li></ul></ul><ul><ul><li>One shell </li></ul></ul><ul><ul><li>Some are terrestrial </li></ul></ul><ul><ul><li>Example members: snails, slugs, nudibranchs </li></ul></ul>
  10. 11. Classes of Mollusks <ul><li>3) Class Cephalopoda </li></ul><ul><li>Fast-moving predators </li></ul><ul><li>Foot is modified into tentacles </li></ul><ul><li>Well-developed nervous system </li></ul><ul><li>Some can use camouflage and jet propulsion (e.g. octopus) when they feel threatened </li></ul><ul><li>Example members: octopus, squid, nautilus, cuttlefish </li></ul>Octopus Nautilus Squid
  11. 12. Form and Function of Mollusks <ul><ul><ul><li>Mollusks vary a lot  clam = representative mollusk </li></ul></ul></ul><ul><ul><ul><li>Digestive system: </li></ul></ul></ul><ul><ul><ul><li>Complete digestive tract (mouth  anus) </li></ul></ul></ul><ul><ul><ul><ul><li>Mouth, esophagus, stomach, intestine, anus </li></ul></ul></ul></ul><ul><ul><ul><li>Have a radula (scraping/drilling organ) or a beak (cephalopods) </li></ul></ul></ul><ul><ul><ul><li>Bivalves trap food in their gills – no radula </li></ul></ul></ul>e.g. Gastropod
  12. 13. Form and Function of Mollusks <ul><ul><ul><li>Respiratory system: </li></ul></ul></ul><ul><ul><ul><li>Aquatic mollusks have gills </li></ul></ul></ul><ul><ul><ul><li>Terrestrial mollusks have a highly folded mantle for O 2 /CO 2 exchange (must stay moist) </li></ul></ul></ul><ul><ul><ul><li>*A clam has incurrent and excurrent siphons  sea water passes through; location of gas exchange </li></ul></ul></ul>
  13. 14. <ul><ul><ul><li>Circulatory system: </li></ul></ul></ul><ul><ul><ul><li>Open circulatory system – the heart pumps blood through open spaces called sinuses instead of through blood vessels </li></ul></ul></ul><ul><ul><ul><li>Excretory system: </li></ul></ul></ul><ul><ul><ul><li>Nephridia (primitive kidneys) remove metabolic waste (nitrogen-containing wastes like NH 3 ) </li></ul></ul></ul><ul><ul><ul><li>Digestive wastes go out anus </li></ul></ul></ul>
  14. 15. <ul><ul><ul><li>Nervous system: </li></ul></ul></ul><ul><ul><ul><li>Bivalves – reduced nervous system; no head </li></ul></ul></ul><ul><ul><ul><li>Gastropods – fairly basic </li></ul></ul></ul><ul><ul><ul><li>Cephalopods – very well developed </li></ul></ul></ul><ul><ul><ul><ul><li>Good vision, small ganglia near mouth, statocysts (balance), simple chemical and touch receptors </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Good dexterity and memory – they can learn! </li></ul></ul></ul></ul>
  15. 16. <ul><ul><ul><li>Musculoskeletal system: </li></ul></ul></ul><ul><ul><ul><li>Muscular foot for movement </li></ul></ul></ul><ul><ul><ul><li>Bivalves – “two shell” ; foot pulls animal forward , and can be sucked back in (for protection) </li></ul></ul></ul><ul><ul><ul><li>Gastropods – “stomach foot” ; they slide forward on broad ventral foot (use muscus) </li></ul></ul></ul><ul><ul><ul><li>Cephalopods – “head foot” ; foot has been modified into many tentacles with suction cups </li></ul></ul></ul>e.g. Gastropod
  16. 18. Ecology of Mollusks <ul><li>Bivalves used to check pollution levels – “environmental monitors” </li></ul><ul><li>Range of lifestyles: predators, scavengers, filter feeders, etc. </li></ul><ul><li>Crop damage – slugs, snails on land </li></ul><ul><li>Ship damage – shipworms in water </li></ul><ul><li>Food source for humans: clams, oysters, mussels, etc. </li></ul><ul><ul><li>Humans can get poisoned by eating mollusks contaminated with toxic protists  cause “red tide” </li></ul></ul>
  17. 19. Video – “Mollusks”
  18. 20. Homework for next class: <ul><li>Complete Ch. 27 Phylum Mollusca worksheet </li></ul><ul><li>Colour Mollusca (clam) diagram – include a legend </li></ul><ul><li>e.g. Excretory </li></ul><ul><li>Circulatory </li></ul><ul><li>Study for Mollusca quiz! </li></ul><ul><li>Read over class notes and check out the class blog: </li></ul>
  19. 21. Works Cited <ul><li>Images taken from the following sources: </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>
  20. 22. Works Cited <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>
  21. 23. Works Cited <ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul><ul><li> </li></ul>