1. PHYLUM MOLLUSCA “MALACOLOGY” The study of molluscs not drab and mundane as found on the N.A. continent of the eight classes, only 3 are common

2. Read 147-156 50,000 -100,000 living species 35,000 extinct species Largest = 1000 lbs. 80% less than 5 cm

3. Classes of Mollusca Class Bivalvia (Clams, oysters) Class Gastropoda (snails, slugs) Class Cephalopoda (Squid, octopus) Class Polyplacophora (Chitons) Additional classes not covered –Class Scaphopoda –Class Caudofoveata –Class Solengastres –Class Monoplacophora

4. Unifying characteristics “INDICATORS OF COMMON ANCESTRY” 1. Visceral mass (internal organs) heart, digestion excretion, reproduction 2. Mantle- tissue surrounding the visceral cavity, secretes shell (which may be present or absent) 3. Muscular foot - organ for propulsion 4. Head- mouth, sense organs, cerebral ganglia 5. Trochophore- juvenile larvae form

5. 6. Radula –Ribbon of small teeth that are used to feed –Made of chitin 7. Siphon 8. Gas exchange through gills Habitat –Fresh and salt water and a few terrestrial

6. Trochophore Larva All the members of this phylum start their life as a free living “trochophore”

7. Generalized Mollusk Anatomy

8. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Source: From A Life of Invertebrates, Copyright © 1979 W. D. Russell-Hunter. Radular Structure

9. Radula

10. http://www.personal.dundee.ac.uk/~a mjones/radula.jpg http://www.wildsingapore.com/chekja wa/pixhtoz/i900b1.gif

11. CLASSES

12. Class Polyplacophora Chitons

13. Class Polyplacophora Eight dorsal plates Reduced head Radula reinforced with iron –Scrape algae from rocks Multiple gills, along sides of body between foot and mantle edge

14. Class Polyplacophora Mantle cavity MouthMouth CtenidiumCtenidium FootFoot AnusAnus

15. Class Polyplacophora MouthMouth DigestiveglandDigestivegland StomachStomachGonadGonad Pericardial cavity NephridiumNephridium AnusAnus

16. Chitons

17. Class Gastropoda Snails, Slugs, Conchs, Limpets

18. Class Gastropoda “STOMACH FOOT” One shell (if present) single muscular foot - operculum- trap door to close for protection - radula- scraping tongue - can be parasites -some can have symbiotic relationship with algae "zooxanthellae”

19. Snail Terrestrial Mantle cavity functions as lung

20. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Internal Structure of a Generalized Gastropod

21. Nudibranch No shell Dorsal projections –Gills –Nematocyst discharge

22. Abalone Several holes in top of shell –Excrete waste Food for man

23. Slug No shell Garden pests

24. Limpet Herbivores Cling to rocks or other surfaces

25. Conch Large shell Marine Many are predators

26. 0060.jpg

27. 0063.jpg

28. Class Bivalvia Clams, Oysters, Shipworms

29. Class Bivalvia Two shells shell has two lateral valves with dorsal hinge Most are filter feeders No head or radula Body enclosed in mantle Head greatly reduced No eyes, a few species with eyes on mantle margin foot usually wedge- shaped Burrow –Sand, wood, rocks

31. Giant Clam & Burrowing Clam Siphon

32. It’s Like a Straw Siphon – tube that sticks out of shell Incurrent siphon takes in water carrying food and oxygen Excurrent siphon carries water containing wastes and CO 2 out

33. Bivalves Gills used to obtain oxygen and to filter out small food particles from the water Adductor muscles keep shells closed As bivalve grows, it adds a layer to its shell

34. Figure 16.31a

35. Scallops

36. Shipworms

37. Class Cephalopoda Squids, Octopuses, Nautiluses

38. Giant Squid “ A live giant squid (Architeuthis) measuring roughly 25 feet long attacks a baited fishing line off the Ogasawara Islands. Japanese scientists recently released the first-ever images of a live giant squid in the wild. Many giant squid have washed up on beaches or have been found dead or dying in fishing nets. This specimen was found in New Zealand in 1996.” http://news.nationalgeographic.com/news/2005/09/0927_050927_ giant_squid.html

39. - Intelligent and have a complex eye (as in humans) can form images by moving the lens in and out (How do we focus?) - chromatophore- pigment sacks with the 3 primary colors. Nerves cause them to expand and contract. (spots to dots) - octopus crawls and squids swim in schools (jet propulsion) Marine

40. Class Cephalopoda Shell in squid and octopus absent or vestigial Ink sac Foot modified into arms and tentacles All predators high extinction 10,000 fossils down to 400 species today

41. Ammonoids Extinct Devonian to Cretaceous –400 to 65 MYA Died out with dinosaurs

42. Squid “you will learn this when we do the dissection” Dorsal Ventral Posterior surface Right Left

43. Squid FinFin ArmArm Funnel (siphon) EyeEye TentacleTentacle CollarCollar

44. Squid Shell (Pen) CtenidiumCtenidium FunnelFunnel SystemicheartSystemicheart Branchial heart

45. Squid Male TestisTestis Hectocotylous arm PenisPenis

46. Squid Female Ovary with eggs Nidamental glands Oviducal gland Oviducal opening

47. Octopus Eight arms with suckers Most intelligent invertebrate

48. Cuttlefish

49. Nautilus (don’t write just look) Up to 94 tentacles –No suckers Shell with many chambers –Lives in outermost chamber

50. Chambered Nautilus

51. But They Don’t Have Shells! How do they protect themselves? Fast swimmers (jet propulsion) –Force water out the mantle cavity through the siphon. The siphon can move and point the animal in any direction Camouflage: Chromatophores Ink Cloud Intelligence Vision

52. Economics Pearls Burrowing shipworms Snails & slugs –Garden pests –Food –Intermediate hosts for parasites

53. Pearl formation Developing pearl EpitheliumEpithelium ShellShell Irritant lodged between shell and mantle Layers of nacre secreted around foreign material

54. Zebra Mussel Environmental Pest Ballast water of ships from Europe in 1986 Attack be secreting adhesive byssal threads –Each other –Other mussels –Man made objects Pipes, plumbing

55. Zebra Mussel Live in high densities Feed on phytoplankton Reproduce rapidly

56. Zebra Mussel Attach to native mussels Killed all native mussels in Lake Erie

57. Distribution of Zebra Mussel