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=ak6MX-QFRVc&

NR=1

http://www.youtube.com/watch?v=SxZbzZ5RE40&feature=related

Cross section

• 1. coelom• 2. dorsal blood

vessel• 3. ventral nerve

cord• 4. muscle layers• 5. typhlosole• 6. nephridia• 7. setae