Annelidae These guys try to worm their way

Annelidae These guys try to worm their way into all ways of life

Typical dissection approach

I. General Characteristics • • A. Bilateral symmetry B. Cephalization C. Coelom D. Complete digestive tract E. Segmentation F. Nephridia G. Circulatory system H. Hydrostatic skeleton

II. Organ systems • A. Digestive System • 1. muscular pharynx • 2. esophagus • 3. crop • 4. gizzard • 5. intestine

B. Nervous system • 1. ganglia • 2. ventral nerve cord

C. Circulatory system • 1. closed circulatory system • 2. dorsal blood vessel • 3. five pairs of pseudohearts • 4. ventral blood vessel • 5. capillary network

D. Reproductive system • 1. hermaphroditic • 2. male parts • 3. swapping of sperm • 4. clitellum • 5. female parts impossible to find for average

The Great Exchange

Fertilized eggs released in a cocoon

E. Excretory system-nepridium • 1. almost every segment has a nepridium

nephridium

III. Classes of annelids • A. Oligochaets • 1. setae not huge • 2. useful for anchorage during locomotion • 3. sequence of muscle contraction

B. Polychaets • 1. parapodia • 2. much more elaborate • 3. locomotion • 4. moving fluid through tubes • 5. excavation in marine worms • 6. respiratory surfaces

Polychaet-feather duster worm

Christmas Tree Worm

C. Hirunidea-leeches • One of man’s best friends

Wonderful story • http: //www. youtube. com/watch? v=ak 6 MXQFRVc&NR=1 http: //www. youtube. com/watch? v=Sx. Zbz. Z 5 RE 40&feat ure=related

Cross section • 1. coelom • 2. dorsal blood vessel • 3. ventral nerve cord • 4. muscle layers • 5. typhlosole • 6. nephridia • 7. setae