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. Lessor Lophotrochozoan 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
Gnathostomula jenneri
Gnathostomula paradoxa

5. Phylum Micrognathozoa

6. Phylum Micrognathozoa
1 species !!!
1st discovered 1994, formally described 2000 mm
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
Chaetonotus simrothi

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

13. Phylum Phoronida
Phoronis hippocrepia
Fig. 21.9
Phoronopsis viridis

14. Phylum Ectoprocta (Bryozoa)
Electra pilosa
Fig
Plumatella repens

15. Bryozoan Micrographs

16. Ectoprocts (Bryozoans)
Bugula sp
Fig

17. Phylum Brachiopoda
Fig

18. Phylum Brachiopoda
Fig