1. Phylum Annelida:
The Annelids

3. Interesting facts Lumbricus terrestris can live up to 6 years
Worms mature in weeks
An earthworm is sexually mature if it has a clitellum
Earthworms can lose their clitellum at the onset of old age or during periods of drought.

4. Characteristics Segmented worms Bilaterally symmetrical Have a coelom
2 body openings
Some have a larval stage
Habitat – marine, freshwater, and terrestrial and are found throughout the world
Not found in frozen soil of polar regions and the dry sand and soil of deserts
Earthworms, leeches, and bristleworms

6. Body Plan of Annelids Tube within a tube
Food is taken into the mouth (opening at anterior end) and wastes are released through the anus (opening at posterior end)
Setae
The anterior segments have become modified according to the habits of the particular annelid.

8. Role of segmentation Most distinguishing characteristic
Segments are continued internally
Internally, each segment is separated from the others by a body partition
Important adaptation

9. Nervous system Simple nervous system
Organs in anterior segments have been modified for sensing the environment
May have a brain in the anterior segment
Nerve cords connect the brain to ganglia in each segment

10. Circulation and respiration
Closed circulatory system
Why must segment worms live in water or in wet areas on land?

11. Hydrostatic skeleton

12. Digestive system
Have a complete internal digestive tract that runs entire length of body
Mouth
Crop
Gizzard
anus

17. Excretion
Have 2 nephridia in each sement

19. reproduction
Hermaprodites.

22. Earthworms are hermaphroditic meaning each worm has organs of both sexes. The male gonopores are usually within the first segments, and the female gonopores are further back, close to the clitellum (the swollen area in adult worms). One worm has to find another worm and they mate juxtaposing opposite gonadal openings exchanging packets of sperm, called spermatophores. Some species also appear to be either parthenogenetic (females producing all females, "virgin birth") or may be able to self-fertilize.

23. The clitellum produces a mucous sheath and nutritive material, and as the sheath slides forward, it picks up ova from the earthworm's ovaries then packets of sperm that had been transferred to the worm from another worm during mating. As the sheath slides off the worm’s head, the ends are sealed to form the cocoon. Initially, the cocoon is quite soft but soon after it is deposited in the soil it becomes slightly amber in color, leather-like and very resistant to drying and damage. 
                              

24. Three classes of annelids

25. Polychaeta

26. Oligochaeta: earthworms
Most well known
Benefits:

27. Hirudinea: The Leeches
Occur mostly in fresh water, some may be marine.
External parasites

28. Medicinal leech Hirudo medicinalis Used to remove excess blood
Continuous harvesting has made them rare in certain areas