1. Phylum Annelida: Segmented Worms
Body divided into repeating segments

2. Phylum Annelida Annelida: annulus- ring, annual
Body appears to be divided into segments
metamerism- each segment contains body systems, excretory, circulatory, nervous, digestive
Bilateral symmetry
two body openings (mouth & anus)
“ True” Eucoelomates-
Live in every environment
Reproduce sexually (hermaphrodites)
8. Setae- hair or bristles- except for leeches
Examples: bristleworms, earthworms, leeches

3. Body Systems No Respiratory- gas exchange through skin *Circulatory
Complete Digestion
Nervous
Muscular
Excretory
Reproductive

4. * Circulatory System Closed – blood always in closed vessel
Five pairs of aortic arches(hearts)
Ventral and dorsal blood vessels and capillaries
Hemoglobin

5. Digestive system Crop-”stomach”- stores food Gizzard- grinds food
Intestine- nutrient absorption
anus

6. Nervous System Pair of cephalic ganglia(bundle of nerves)
Ventral nerve cord with ganglia in each segment (segmental ganglia)

7. Muscular System Longitudinal and Circular muscles
Allows for better movement- can thrash and inch, raise head, etc.

8. Body wall
Epithelium
Circular muscle
Longitudinal muscle

9. Excretory System
Wastes processed through two nephridia(kidney) in each segment
Nephridia, bladder and excretory pore

10. Fig
Fig

11. Reproductive System -Hermaphrodites -sexual reproduction
- trochophore larvae

12. Trochophore larva- paddlelike, bristles
Apical tuft
Stomach
Ciliary band
Mouth
Anus

13. Annelid development

14. Class Polychaeta Many setae(bristles) Parapodia(paddlelike appendages
Marine
Gonads only appear during breeding season
Predators of small animals, prey for larger

15. Class Polychaeta
Parapodium
Head
Tentacle

16. Polychaete Worm Predatory
Jaw
Tentacle
Everted pharynx
Palp
Eye
Cirrus
Parapodium

17. Class Polychaeta Fireworm

18. Sedentary Polychaete Lugworm
Fig. 17.5

19. Fig. 17.4

20.
PEACOCK WORM VIDEO

21. Class Oligochaeta Few setae(bristles) Clitellum No parapodia
Hermaphroditic
Decomposers (aerate soil)
food for larger animal
Ex. Giant Gippsland earthworm, earthworms

22. External Structures of an Earthworm
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External Structures of an Earthworm

23. Lumbricus terrestris Feed on decaying organic matter Enrich soil

24. Fig. 17.1

25. Internal Structures of an Earthworm
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Internal Structures of an Earthworm

26. Fig c

27. Earthworms Digestive structures:
Crop: temporary storage sac after mouth
Gizzard: sac with muscular walls to grind soil
Intestine: stretches length of body to aid in digestion of soil
Anus: wastes are removed
Other structures:
Setae: bristles used for movement (ventral side)
Clittelum: enlarged segment; secretes mucus & contains reproductive parts
Anus
Setae
gizzard
crop
Clittelum
Mouth

28. Earthworm Reproduction-sexual
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Earthworm Reproduction-sexual

30. Class Hirudinea Anterior & posterior sucker-ectoparasite No setae
hermaphrodites
Most live in fresh water
Dorsoventrally compressed(flat)
Ex. leeches
Feed
Invertebrates
Body fluids
Blood

31. Fig

32. Leeches Parasitic segmented worm Most live in fresh water
Have no bristles for movement
move with muscular contractions
Suckers used for attachment to host
Some have suckers on tail also

33. Secrete anesthetic during bite and release anticoagulant into blood during feeding (to keep blood flowing)
Leeches were used in medical procedures years ago to “bleed” the sick
remove “bad blood”
now they are used in cosmetic surgery, digit and limb reattachment, and blood removal from bruises