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The Lesser Protostomes

The Lesser Protostomes. The Lesser Protostomes. Phyla contain few numbers of species All phyla are aquatic organisms Recorded in the fossil record – especially fossil beds such as the Burgess shale

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The Lesser Protostomes

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  1. The Lesser Protostomes

  2. The Lesser Protostomes • Phyla contain few numbers of species • All phyla are aquatic organisms • Recorded in the fossil record – especially fossil beds such as the Burgess shale • Morphologies are intermediate to the morphologies of the major lophotrochozoa phyla Mollusca, Annelida and the Ecdyzoa phylum Arthropoda

  3. LessorLophotrochozoan Phyla

  4. Phylum Gnathostomulida • 1st discovered 1928, formally described 1956 • 18 genera, 80 species • 0.5-1mm • Feed on bacteria, fungal, & protozoan cells in sediment • Aceolomic • Incomplete digestive tract • Monociliated epidermal cells Gnathostomulajenneri Gnathostomula paradoxa

  5. Phylum Micrognathozoa

  6. Phylum Micrognathozoa • 1 species !!! • 1st discovered 1994, formally described 2000 • 0.1-0.2mm • Complete gut • Complex jaw • Only females found • Parthenogenetic ?

  7. Phylum Rotifera • ~2000 species • Corona of ciliated cells • Pseudoceolomic • Central nervous system • Complete gut • Many species are female only • Parthenogenetic

  8. Phylum Rotifera • Rotifer YouTube Movie

  9. Parthenogenetic Reproduction • Females are diploid • Amictic eggs • Produced by mitosis • Are not fertilized • Mictic eggs • Produced by meiosis • Develop w/o fertilization into haploid male • Fertilized mictic eggs enter dormancy

  10. Phylum Acanthocephala

  11. Phylum Gastrotricha • ~500 species • 0.06-0.5mm • Feed on bacteria & protozoa • Hermaphroditic • Freshwater species parthenogenetic Chaetonotussimrothi

  12. Phylum Cycliophora Simbion pandora • Discovered 1995 • 0.35-.1mm • Live on mouthparts of marine decapod crustaceans

  13. Phylum Phoronida Phoronis hippocrepia Phoronopsis viridis

  14. Phylum Ectoprocta (Bryozoa) Electra pilosa Plumatella repens

  15. Bryozoan Micrographs

  16. Ectoprocts (Bryozoans) Bugula sp

  17. Phylum Brachiopoda

  18. Phylum Brachiopoda

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