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Phylum Annelida

Phylum Annelida. Phylum Annelida. Ancestral Traits Coelomate Lophotrochozoan Protostome Closed circulatory system Cephalization Derived Traits Segmentation Metamerism Septa Setae Bristles Myelinated neurons. Spirobranchus giganteus Christmas tree worm. ~ 40K species of annelids.

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Phylum Annelida

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  1. Phylum Annelida

  2. Phylum Annelida • Ancestral Traits • Coelomate • Lophotrochozoan • Protostome • Closed circulatory system • Cephalization • Derived Traits • Segmentation • Metamerism • Septa • Setae • Bristles • Myelinated neurons Spirobranchus giganteusChristmas tree worm ~ 40K species of annelids

  3. Annelid Taxomony • Class Polychaeta (many bristles) • most numerous # species • marine Hermodice crunculata

  4. Annelid Taxomony • Class Polychaeta • Class Oligochaeta (few bristles) • Freshwater, marine & terrestrial Lumbricus terrestris

  5. Annelid Taxomony • Class Polychaeta • Class Oligochaeta • Class Hirudinea • Fixed # segments (34) • Setae absent Hirudo medicinalis

  6. Annelid Phylogeny

  7. Annelid Body Plan Setae

  8. Class Polychaeta • Highly specialized head regions • Antennae • Sensory palps • Feeding appendages • Paired extensions of body(parapodia) • Often tube-dwelling • Burrow into substrate and secrete mucus/CO3 materials Bispira bunnea sabellid worm

  9. Polychaete Anatomy

  10. Polychaete Anatomy (cross section)

  11. Polychaeta Amphitrite

  12. Polychaeta Lugworm (Arenicola sp)

  13. Polychaeta

  14. Polychaeta

  15. Clade Siboglinidae (Phylum Pogonophora) Riftia pachyptila Ridgea sp

  16. Giant tube worms (Vestimentifera) trophosome Riftia pachyptila

  17. Polychaete Reproduction • Dioecious • Trochophore larvae • Some species develop specialized segments containing gametes • Epitokes • Segments are released and gametes burst out

  18. Polychaete Asexual Reproduction • Epitokes are essentially buds • Clues to ancestral origin of segmentation • Segmentation may have been derived from incomplete budding processes

  19. Class Oligochaeta

  20. Oligochaete Anatomy

  21. Oligochaete Anatomy

  22. Seta: a.k.a. Bristles

  23. Oligochaete Excretory System

  24. Oligochaete Nervous System

  25. Oligochaete Nerve Cord

  26. Oligochaete Reproduction

  27. Oligochaete Development • For terrestrial oligochaetes, development is direct without any larval forms • Some aquatic oligochaetes retain a trochophore-like larval stage

  28. Common Terrestrial Oligocheates: Earthworms • Octagonal-tail worm (Dendrobaena octaedra) • Red marsh worm (Lumbricus rubellus) • Dew-worm or nightcrawler (Lumbricus terrestris) • Pink soil worm (Aporrectodea rosea) • Canadian worm (Aporrectodea tuberculata) • Pasture worm (Aporrectodea turgida) • Woodland white worm (Octolasion tyrtaeum) • Redworm (Eisenia fetida )

  29. Quick and Easy Earthworm Morphology Guide Morphology Number & location of GTs and TPs, location & shape of clitellum Ecology Location of burrows Aporrectodea turgida Lumbricus rubellus

  30. Aquatic Oligocheates

  31. Class Hirudinea

  32. Hirudo medicinalis

  33. Phylum Sipuncula • ~250 species • Trochophore larvae

  34. Sipunculan Internal Structures

  35. Phylum Echiura • ~140 species • Closed circulatory system • Trochophore larvae Echiurus sp

  36. Phylum Echiura Bonellia viridis

  37. Echiuran Anatomy

  38. Oddities • Sex determination & dimorphism in echiurans

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