Chapter 29: Mollusks and Annelids

1. Chapter 29: Mollusks and Annelids What is a mollusk? What is an annelid?

2. Mollusks

4. Objectives: • Describe the skeletal structure, fertilization, reproduction, body symmetry, body coverings and locomotion for the Phylum Mollusca and Phylum Annelida • This will be completed through spreadsheet notes…..

5. How are annelids and mollusks related? • Both were the first major groups of animals to develop: • true coelom. – they have a body cavity, the gut and the rest of the organs are cushioned by the fluid in the coelom. • trocophore: a larval stage develops from egg, in some species it is free swimming and propels itself with cilia.

6. Trochophore: Free swimming larval stage of mollusks and annelids

7. Seven classes of mollusks make up phylum Mollusca • Three largest classes and examples are: • Gastropods- snails and slugs • Bivalvia- clams, oyster, and scallops • Cephalopoda- octopuses and squids

8. Know the 6 Key Characteristics of Mollusks • 1. Body cavity: true coelom • 2. Symmetry: bilateral symmetry • 3. Three-part body plan: visceral mass- central part, mantle- outer layer of body, foot- muscular region used for locomotion • 4. Organ systems- excretion, circulation, respiration, digestion, reproduction • 5. Shell- one or two shells (most) • 6. Radula- tongue like organ in the mouth, thousands of teeth on radula scrap off food and pull in prey.

15. Mollusk - Gastropods Examples: snails,slugs

16. Fertilization and Reproduction for Gastropods: same as mollusks

19. Body symmetry of gastropods is bilateral

20. Body coverings of gastropods are a mantle of tissue covering the body, spiral shells

21. Locomotion of Gastropods:"foot", secretes mucus it glides on

22. Bivalves:Examples: clams, oysters, scallops (all the notes for the next 6 slides are in the bivalve row)

23. Bivalve skeletal structure: • All have two part hinged shell Giant clams can weigh more than 227 kilograms (500 pounds), and are the largest bivalve mollusk in the world.

24. Fertilization and Reproduction of Bivalves: sexually, release sperm and egg into water, fertilized eggs become trocophore larvae

25. Important features of Bivalves: filter feeders, through siphon tube, over gills out other siphon tube

26. Body symmetry of bivalves is bilateral

27. Body coverings of bivales: two part hinged shell, two thick adductor muscles connect shells

28. Locomotion of bivalves: most sessile, some swim opening/closing valves quickly

29. Cephalopod examples: squids, octopuses, cuttlefish, nautilus

30. Cephalopod skeletal structure:large head attached to tentacles, lack external shell,

31. Cephalopod reproduction: Sexual

32. Cephalopod body symmetry: bilateral

33. Cephalopod body coverings: only nautilus has shell

34. Cephalopod locomotion: jet propulsion

36. Annelids:

38. Important features of annelids:respire through skin, have closed circulatory system, complex nervous system

39. Body symmetry of Annelids: bilateral

40. Body coverings of annelids: setae: bristles, some have parapodia: fleshy appendages

41. Body coverings of annelids: setae: bristles, some have parapodia: fleshy appendages

42. Locomotion of annelids: fluid filled compartment aids with contracting, stretching to move

43. Marine worms: Examples feather dusters, Nereis

44. Marine worm skeletal structure: Many parapodia

45. Marine Worm Reproduction: Hermaphrodites, sexual

46. Marine worm special features:some burrow, others live in protective tubes, some feed by pumping water through body

47. Body symmetry of Marine worm: Bilateral

48. Body coverings and locomotion of marine worms: many parapodia, use parapodia to swim, burrow or crawl

49. Earthworms skeletal structures: no parapodia, only setae