2. Class Errantia (nee Polychaeta) Class Sedentaria
Ch 11 Phylum Annelida
The segmented worms
Class Errantia (nee Polychaeta) Class Sedentaria

3. The Cambrian Explosion

4. Key Characteristics
coelomates
segmented
hydrostatic skeleton

5. Basic Body Plan ventral blood vessels longitudinal muscle
dorsal blood vessel
circular
coelom
intestine
ventral nerve cord
setae
nephridium
nephridiopore

6. Integrated Nervous System
Annelid Nervous System
Integrated Nervous System

7. Annelid Excretory System
Metanephridia

8. Marine Annelid Reproduction
Trochophore Larva

9. predators or filter feeders
Class Errantia
marine
parapodia & setae
predators or filter feeders
reproduce via epitoke
Clade Siboglinidae

10. Crawlers & Swimmers

11. Parapodia and Setae

12. Longitudinal muscles
Setae
muscles
Parapodium
Oblique muscles

13. Movement

14. Epitoke

15. Epitoke

17. Bearded fireworm (Hermodice carunculata)
Venomous white bristles extended in defense

18. Tube or Burrow Dwellers
Class Sedentaria
Tube or Burrow Dwellers

19. Siboglinidae (Pogonophorans = “beardworms”)
Bilateral symmetry
No mouth, no digestive system
Absorb some nutrients via tentacles
Deep sea dwellers
Obtain most energy needs via hydrogen sulfide oxidizing bacteria
So - why are they considered to be annelids?

20. Affinities with Annelids metameric segmentation of opisthosoma
molecular analyses
metameric segmentation of opisthosoma
photoreceptor cells
chitinous cuticle
setae

21. spoon worms and innkeepers Closed circulatory system
Echiuridae
spoon worms and innkeepers
bilateral
Closed circulatory system
1-3 pairs of nephridia
unsegmented
trocophore larva

23. Polychaete Sedentaria
Christmas tree worm (Spirobranchus giganteus), abundant in the Caribbbean
The two spiral crowns can retract into a tube, which is covered by the operculum

24. Polychaete Sedentaria
Social feather duster (Bispira brunnea) grows in clusters
Common in the Caribbean

25. Polychaete Sedentaria
Social feather duster (Bispira brunnea) with crowns of radioles extending from parchment-like tubes
Light brown color characteristic in Belize

26. Polychaete Sedentaria
Split-crown feather duster (Anamobaea orstedii), common in the Caribbean
When disturbed, worm retreats into parchment tube

28. Epigeic Endogenic Anecic
Oligochaeta
Epigeic Endogenic Anecic

29. Feeding & Digestion

30. Setae

31. Earthworm Locomotion

32. Earthworm Reproduction

33. Aquatic Oligochaetes - Tubifex

34. Whirling Disease
Tubifex worms ingest microscopic spores laying on river bottom. The spores hatch and the protozoan-like parasite is released into the water.
Parasite burrows through the skin of the trout, mates, and releases small larvae which migrate to the nervous system. When larvae reach the brain, attack cartilage, develop into spores. Infected fish develop characteristic “whirling” behavior and die, releasing spores to repeat the cycle.

35. Hirudinea gut nerve cord sinus circular muscle diagonal muscle caecum
dorso-ventral muscle
longitudinal muscle

36. Leech Reproduction

37. Movement

38. Phylum Sipuncula

39. entirely marine and benthic no circulatory or respiratory systems
bilateral
unsegmented
tentacles
one pair of nephridia
introvert
entirely marine and benthic
no circulatory or respiratory systems