1. Phylum Annelida The Segmented Worms

2. Classes of Annelida Class Polychaeta (fanworms, clam worms) Class Polychaeta (fanworms, clam worms) Class Oligochaeta (earthworms) Class Oligochaeta (earthworms) Class Hirudinea (Leeches) Class Hirudinea (Leeches) Classes not covered Classes not covered Class Branchiobdellida Class Branchiobdellida Class Acanthobdellida Class Acanthobdellida

3. General Characteristics Annelids are to be found in marine, freshwater, and terrestrial habitats Annelids are to be found in marine, freshwater, and terrestrial habitats The body is vermiform, bilaterally symmetrical, and segmented The body is vermiform, bilaterally symmetrical, and segmented Each segment is separated from contiguous ones by a transverse septum Each segment is separated from contiguous ones by a transverse septum The body is triploblastic with a well developed coelom The body is triploblastic with a well developed coelom The body is covered with a flexible non-chitinous cuticle The body is covered with a flexible non-chitinous cuticle

4. General Characteristics Most forms have setae, hard, bristle-like chitinous structures Most forms have setae, hard, bristle-like chitinous structures Digestive system is complete Digestive system is complete Circulatory system is closed, Circulatory system is closed, Excretory system typically consists of a pair of nephridia per segment Excretory system typically consists of a pair of nephridia per segment

5. Typical Arrangement of Segments

6. Class - Polychaeta Feather Duster worms, Clam worms, Christmas Tree worms

7. General Characteristics Mostly marine and free-living Mostly marine and free-living Many setae, on fleshy lateral outgrowths of the body wall known as parapodia Many setae, on fleshy lateral outgrowths of the body wall known as parapodia Well developed head bearing appendages Well developed head bearing appendages Sexes separate, with a free-swimming trochophore larva Sexes separate, with a free-swimming trochophore larva

9. Nereis

10. Parapodium Parapodia

11. Figure 17.03d

12. Some Polychaets

13. Figure 17.co

14. Figure 17.02a

15. Figure 17.02b

18. Figure 17.09

19. Class Oligochaeta Earthworms and Freshwater Worms

20. General Characteristics Are terrestrial with a few freshwater species Are terrestrial with a few freshwater species Have few setae Have few setae No parapodia No parapodia No distinct head appendages No distinct head appendages Clitellum present Clitellum present Hermaphrodites, with copulation required Hermaphrodites, with copulation required Eggs are deposited in a cocoon and development is direct Eggs are deposited in a cocoon and development is direct

21. Figure 17.12a

23. Earthworm Dissection

26. Figure 17.12c

27. Figure 17.14

28. Figure 17.15

29. Figure 17.17

30. Some Oligochaets

32. Figure 17.18b

33. Figure 17.18c

34. Figure 17.18d

35. Figure 17.17g

36. Class Hirudinea

37. General Characteristics Ectoparasites, not all - many feed on organic debris Ectoparasites, not all - many feed on organic debris Usually dorso-ventrally flattened with fixed number of body segments (34) Usually dorso-ventrally flattened with fixed number of body segments (34) No setae or parapodia No setae or parapodia Clitellum present only during reproduction Clitellum present only during reproduction Two suckers – anterior and posterior Two suckers – anterior and posterior

38. Figure 17.20