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Nine minor phyla to consider

Three major protostomous eucoelomate phyla. Nine minor phyla to consider. Problematic Phyla. Mixture of characters Where to put them Did segmentation evolve once or many times? What to do with organisms with both protostome and deutrostome characteristics?

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Nine minor phyla to consider

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  1. Three major protostomous eucoelomate phyla Nine minor phyla to consider

  2. Problematic Phyla • Mixture of characters • Where to put them • Did segmentation evolve once or many times? • What to do with organisms with both protostome and deutrostome characteristics? • What to do if molecular techniques contradict morphological evidence?

  3. Two groupings • Lophotrochozoans • Sipuncula - peanut worms • Echiura – spoon worms • Lophophore worms • Phoronida – lophophorate worms • Ectoprocta – bryozoans or moss animals • Brachiopoda – lamp shells • And annelids and mollusks in some classifications Marine benthic worms

  4. Two groupings • Ecdysozoans • Pentastomida – tongue worms • Onychophora – velvet worms • Tardigradia – water bears • Chaetoghatha – arrow worms • And arthropods + others in some classifications Unclear position

  5. Phylum Sipuncula • Peanut worms • Disturbed contract into peanut shape • 250 benthic species • Tentacled proboscis • Collect organic matter on mucus • Not metameric • No setae • Trochophore larvae

  6. Phylum Echiura • Marine worms • Spoon worms • 160 species • Organic material collected in gutter • Moved to mouth • Closed circulation • Setae • No metamerism

  7. Phylum Echiura -- the ciliated probocis can be quite large -- detritus feeders

  8. Internal anatomy • Multiple pair nephridium • Suggest segmentation • Relation to annelids

  9. Lophophorates • Lophophore • Cilliated tentacles on a ridge • Surround mouth • Not anus • U-shaped digestive tract • Anus outside tentacles • Coelom divided into 3 parts

  10. Phylum Phoronida • 10 species • Leathery or chitinous tube • Coelom divided into 3 parts • Protocoel • Mesocoel • Metacoel • Similar to deutrostomes • Closed circulation • No heart

  11. Phylum Brachipoda • Bivalve like shell • Lamp shells • Lophophore inside shell • 12 000 fossil species • 325 living species • Open circulation • Heart • Deutrostome like development

  12. Phylum Ectoprocta • Bryozoa • 4000 species • Very small • Mostly less than 0.5mm • Colonial • biofoulants • Can have stiffened body wall • Respiratory, vascular and excretory organs absent

  13. Ecdysozoan group • Molting animals • Cuticle shell • Includes arthropods and nematodes • Separate sexes

  14. Phylum Pentastomida • Tongue worms • 5 mouth parts • 130 worms • Parasites vertebrate respiratory system • Segmented appearance • Some argue related to Branchiura • Lack organs for respiration, circulation, excretion

  15. Phylum Onychophora • Velvet worms • 70 species • Paired appendages • Biramous • Have annelid and arthropod characteristics

  16. OnychophoraInsect/arthropod characters • Trachea with spiracles • Cuticle not true exoskeleton • Single pair antennae • Open circulation

  17. OnychophoraAnnelid characters • Segmentally arranged nephridia • Muscular pody wall • Annelid like eye

  18. Phylum Tardigradia • Water bears • 300-400 species • Arthropod like characters • Muscles attach to exoskeleton • Malphagian tubules video

  19. Arthropoda + Pentastomida Annelida Onychophora Tardigrada 2) nephridia replaced by Malpighian glands 1) muscles attach to exoskeleton 3) growth by ecdysis 2) haemocoel and open circulation 1) a tracheal system with numerous spiracles From Fig. 13.13

  20. Phylum Chaetognatha • Deutrostome-like development • Molecular evidence suggests relation to nematodes

  21. Phylum Chaetegnatha • Arrow worms • Pelagic marine worm • Name – spines around mouth • Spines snap down on prey • Important predator copepods and fish • 65 species • Up to 10 cm

  22. Protostomes give rise to Deuterostomes

  23. Chordata Cephalochordata Vertebrata Urochordata Hemichordata Echinodermata Vertebrae Chordate characteristics throughout life Notochord Tadpole like larvae with post-anal tail Dorsal Hollow Nerve Chord Gill Slits in pharynx Deuterostomes

  24. Deutrostomes • Phylum Echinodermata • Phylum Hemichordata • Phylum Chordata • Subphylum Urochordata • Subphylum Cephalochordata • Subphylum Vertebrata

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