1. Phylum Annelida Segmented Worms Leech Christmas tree worm Fireworm
Feather duster worm

2. Annelid Characteristics
Segmentation = Metamerism
metameres (=somites, segments)
Show true segmentation - both internal and external
Allows for specialization

3. Annelid Systems All systems found in Annelids but skeletal
Complete digestive tract - some specialization - crop and gizzard
Closed circulatory system - is segmentally arranged dorsal and ventral vessels aortic arches (hearts)

4. Annelid Systems All systems found in Annelids but skeletal
Excretion
Nephridia - segmentally arranged

5. Annelid Systems All systems found in Annelids but skeletal
Nervous system
ladder shaped
pair of cerebral ganglia
double ventral nerve cords
pair of ganglia in each segment
several sensory structures
taste buds
tactile organs
eyes in some
statocyst

6. Annelid Systems Reproduction some are monoecious, others dioecious
marine species have trochophore larvae
some have asexual reproduction by
Budding
fragmentation

7. Annelid Systems Respiration across body surfaces some have gills
some use parapodia

8. Class Polychaeta Make up 2/3 of phylum
most primitive annelids; ancestral to other two classes
almost all are marine, few freshwater species

9. Polychaet Characteristics
differentiated head
Tentacles
first segment
Prostomium
Peristomium
Mouth
Palps
eyes

10. Polychaet Characteristics
Parapodia- lateral appendages
notopodium- dorsal
neuropodium- ventral
acicula- rods
Respiration
By parapodia

11. Polychaet Characteristics
Reproduction
sexes separate
no permanent gonads
egg and sperm form from coelomic peritoneum
pass out of nephridia or burst thru body wall
fertilization is external in sea
free swimming larva- trochophore

12. Polychaet Ecological Types
free living- all are predators
tube dwelling- all are filter feeders
secrete their own tube
burrow into substrate

13. Class - Oligochaeta Terrestrial or Freshwater
No distinct head - but contains pro- and peri- stomium
Clitellum - present at all times
Used in copulation
Cocoon production

14. Class - Oligochaeta Reproduction Monoecious Copulation
Internal fertilization
Eggs laid in cocoon
no larval stage

15. Class - Oligochaeta Digestive system - well differentiated mouth
pharynx
crop
gizzard
intestine - Typhlosole
Anus

16. Class - Oligochaeta Circulatory system Respiration Excretion Closed
5 pairs of aortic arches
Hemoglobin
Respiration
Body surface
Excretion
Nephridia

17. Class - Hirudinea Freshwater or terrestrial Have suckers
Segmentation fixed (34 segments)
Clitellum only during season
Digestive tract
large crop
Anticoagulant
Medically important