1. Phylum Annelida The Segmented Worms
Class Polychaeta – feather dusters
Class Clitellata
Subclass Oligochaeta – earthworms
Subclass Hirudinea – leeches
Class Echiura – spoon worms

4. Annelus: Lt.“ring”, as in “annuli” of trees/reptile bones/clam shells
Cephalization! Well-developed nervous system: nerve cord with ganglion in each segment and anterior brain
Bilaterally symmetrical
Organs within a true coelom (cavity within mesoderm)
Compartmentalization of organs / movement of parts of body
Closed circulatory system with five pairs of “aortic arches”

5. Sophisticated digestive system:
mouth – food enters
pharynx – passes through
esophagus – peristalsis
crop – storage
gizzard – grinding
intestine – more digestion
anus – waste exits

6. Earthworm anatomy
Intestine
Gizzard
Esophogus
Crop
Pharynx
Mouth

7. Appendages: Setae &/or parapodia
Nephridia remove nitrogenous wastes; wets skin
No lungs - use diffusion, some have simple gills
Most have red hemoglobin in blood (very efficient)

8. Most are hermaphroditic
testes in 10th and 11th
ovaries in 13th with seminal vesicles and receptacles for sperm storage
Clitellum produces “slime band” protective coat around eggs

10. Major Classes of Annelids
Class Polychaeta (“many hairs”) (~12,000 species): bristleworms, tube worms, featherdusters
marine worms with parapodia and (most) jaws!
Class Clitellata (~10,000 species)
Subclass Oligochaeta (means “long hair”): earthworms, nightcrawlers, (aquatic) tubifex worms
20-45 tons of soil/year/acre processed by worms on organic farms
each worm processes its own weight each day
Subclass Hirudinea (Latin: hirudo = leech):
terrestrial / aquatic leeches
some parasitic, some free-living
medicinal anticoagulant “hirudin”

11. An aquatic oligochaete host of whirling disease

13. Class Polychaeta

14. A filter-feeding polychaete: feather-duster

15. The Bobbit Worm (polychaete)

16. Bristle-worm (nereis, polychaete)

17. Nereis closeup

18. Methane hydrate deposits on the ocean floor teem with life
Methane hydrate deposits on the ocean floor teem with life. Residents include ferocious polychaete ice worms that burrow into the formations and defend their lairs against intruders.

19. Fanworm

20. Class Hirudinea
The medicinal leech is best known as the organism used for blood letting (people used to believe many health problems caused by "bad" blood). They are being used once again to remove blood from hematomas (areas of blood leakage) resulting from surgery (like re-attaching severed limbs, etc.).

21. Most cool website:

24. Spoon Worms:
Class Echiura