1. Annelids
Segmented Worms

2. Vocabulary
pharynx esophagus sperm receptacle gizzard nephridia aortic arch crop oviducts septum setae clitellum parapodia Polychaeta Oligochaeta Hirudinea

3. Oligochaeta “Few bristles” Earthworms Terrestrial
Few setae, no parapodia

4. Giant Gippsland Earthworm
Up to 13 feet long!
Found only in small region in southeast Victoria, Australia

5. Polychaeta “Many bristles” Marine annelids
Free living or tube dwelling
Largest class
Parapodia
Movement
Increases SA for gas exch.

6. Polychaeta
Parapodia
(Up close and personal!)

7. Hirudinea Leeches No setae or parapodia Mostly parasites
Inject anesthesia
Gain 10x body weight

8. Annelids in the Environment
Food chain
Earthworms aerate soil –
Provide organic matter (castings)  “poop”
Leeches – medical uses

9. General Characteristics
Segmentation allows for more specialization
Each septum limits diffusion
Bilateral symmetry
Hydrostatic skeleton
Coelomates

10. Body Systems

11. Digestion Specialized organs
More efficient digestion because each organ has a specific function

12. Digestion Mouth – eat Pharynx – swallow Esophagus – connect
Crop – storage
Gizzard – grind
Intestine - digest/absorb
Anus – release castings

13. Circulation Closed system of blood vessels Carries nutrients, O2
Thicker, larger animals!
Dorsal blood vessel
Ventral blood vessel
5 “hearts” (aortic arches)

14. Circulation and Other Systems

15. Excretion Nephridia – two excretory tubes per segment
Nitrogenous waste and excess water are removed via nephridia
Water/waste exit through excretory pores

16. Nervous Anterior “brain” Ventral nerve cord, with segmental branches
Senses: receptors for light, moisture, T°, vibrations

17. Reproduction Hermaphrodites – DO NOT self-fertilize!
Each passes sperm to other worm’s sperm receptacle

18. Reproduction Mucus cocoon is secreted from clitellum
Rolls off anterior end
Collects eggs/sperm as it rolls
Becomes egg capsule

19. Earthworm Dissection

20. Earthworm Dissection

21. Compare the Guide and Reality