Annelidae
These guys try to worm their way
into all ways of life
Typical dissection approach
I. General Characteristics
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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=ak6MXQFRVc&NR=1
http://www.youtube.com/watch?v=SxZbzZ5RE40&feat
ure=related
Cross section
• 1. coelom
• 2. dorsal blood
vessel
• 3. ventral nerve
cord
• 4. muscle layers
• 5. typhlosole
• 6. nephridia
• 7. setae