1. Phylum Annelida

2. Phylum Annelida contains three classes:
Polychaeta
Oligochaeta
Hirudinida
Annelid characteristics include:
Paired epidermal setae
Bilateral Symmetry
Coelom divided by septa
Metamerism
Circular and longitudinal muscles
Nervous system with dorsal cerebral ganglia and ventral nerve cord
Closed circulatory system
Excretory system (paired nephridia in each segment)

3. Class Polychaeta Distinct head with eyes and tentacles
Gr. polys, many, + chaite, long hair
Distinct head with eyes and tentacles
Most segments with parapodia
Many setae present in tufts on parapodia
Clitellum absent
Usually dioecious
Examples: Nereis

4. Fig. 17.5

5. Fig. 17.6

6. Fig. 17.7

7. Fig. 17.8

9. Figure: 16_30b
Title:
Annelids
Caption:
(b) The “fireworm” polychaete swims by using paddles on each segment. The bristles on each paddle can deliver a fiery sting.

10. CO 17

11. Fig. 17.9

12. Fig

13. Fig a

14. Fig. 17.4

15. Figure: 16_30a
Title:
Annelids
Caption:
(a) A polychaete annelid projects brightly spiraling gills from a tube, made by the worm and attached to rock. When the gills retract, the tube is covered by a “trap door” visible as a reddish collar encircling the top of the tube.

17. Fig

18. Fig

19. Fig

20. Class Oligochaeta Head absent Segments without parapodia
Gr. oligos, few, + chaite, long hair
Head absent
Segments without parapodia
Few setae per segment
Clitellum present
Monoecious
Examples: Lumbricus, Tubifex

22. Fig

24. Fig

25. Class Hirudinida Setae absent Body with 34 segments
Anterior and posterior suckers
Clitellum present only during breeding season
Monoecious
Examples: Hirudo

26. Figure: 16_30c
Title:
Annelids
Caption:
(c) This leech, a freshwater annelid, shows numerous segments. The whitish disk is a sucker encircling its mouth, allowing it to attach to its prey.

27. Fig

29. Fig