1. Phylum Annelida
Phylum Annelida p

2. Characteristics Segmented worms Cylindrical Less than ½ mm  3 metres
3 germ layers, bilateral, coelomate
Vary in colour, patterning, & other superficial features
Many segments are separated by internal walls (septa)
Includes: C. Polychaeta – sandworms, bloodworms
C. Oligochaeta – Earthworms
C. Hirudinea - Leeches

3. Body Systems Digestive System:
Herbivores, carnivores, & detritus feeders
Two openings
More complex
For example - Earthworm:
Mouth  pharynx  esophagus  crop  gizzard  intestine  anus

4. Mobility: Respiration:
2 muscle groups: longitudinal muscles & muscles that circle the body
Respiration:
Some aquatic use gills
Some respire through their skin using diffusion
Note: Terrestrial annelids require moist skin so secrete a cuticle.

5. Internal Transport: Closed circulatory system
Blood moves to head through dorsal blood vessel
Blood moves to tail through ventral blood vessel
Blood moves through body by one of two methods:
Muscle contractions
“hearts” (larger ring vessels) that pump

6. Excretion: Response: Solid wastes via anus
Liquid wastes (metabolic wastes) by nephridia
Response:
Well developed nervous system
2 large nerves connected to a brain by a pair of ganglia
From ganglia, ventral nerve cord runs the length of the body
Variety of sense organs

7. Reproduction: Most sexual Few asexual (budding)
Separate sexes & external fertilization
Hermaphroditic & internal fertilization
Few asexual (budding)

9. Ecological Role Human parasites (leech) Leeches in medicine
Bloodletting
Reattachment & skin grafts
As a food source
To condition & aerate the soil (ex. Earthworms)