1. Acrobeles complexus Ch 11 Pseudocoelomates Ch 11 Pseudocoelomates “soo-doe-see-low-mates”

4. Pseudocoelomates (Aschelminthes) 7 phyla: Do not molt –Rotifera –Acanthocephala Molt –Nematoda –Nematomorpha –Kinoryncha –Loricifera –Priapulida

5. Phylogeny Two Hypothesis 1.Phyla related based on anatomy, pseudocoelom, cuticle, muscular pharynx, and adhesive glands. 2.Phyla not related, thus are polyphyletic absence in single unique feature  independent evolution a. similarities result of convergent evolution in similar environments.

6. Pseudocoelomates Plant ectoparasite A. lumbricoides A heterogeneous group: –Size: microscopic  several meters – some are exclusively marine; some (e.g., nematodes) live in a variety of habitats, esp. soil; and some are exclusively parasitic

7. Pseudocoelomates Common characteristics: 1.First animal to posses a distinct body cavity, but they lack the peritoneal lining and membranes (mesenteries) 2.Pseudocoelom- fluid filled, gelatinous substance, serves for circulation, aids in digestion, acts as hydroskeleton.

8. Common characteristics: 1)Pseudocoelom body cavity (pseudocoelom/ pseudocoel) a space b/w gut and mesodermal components of body wall Body cavity is not lined with a mesodermal sheet –Does not cover inner surface of body wall

9. Common characteristics: 1)Pseudocoelom Pseudocoelom is spacious, fluid-filled and Contains visceral organs No muscular tissue associated with gut tract No membranes suspend organs in body cavity

10. Common characteristics: 2)Eutely Eutely (thrift) a condition in which the number of cells is constant (i.e. C. elegans = 959 adult)

11. http://www.wormatlas.org/handbook/alimentary/alimentary2.htm Common characteristics: 3)complete digestive tract (mouth and anus) Found in most other higher animals

12. Common characteristics: 1.Bilateral symmetry 2.Unsegmented, tribploblastic, and cylindrical in cross section 3.Protonephridia 4.Some cephalization is evident (primitive brain, mouth, sense organs) 5.Dioecious 6.Complete digestive tract (mouth and anus) 7.All have cuticle

13. Evolutionary advantages of pseudocoel: –Greater freedom of movement –Space for development and differentiation of organ systems (ie. digestive, excretory) differentiation: process by which cells become different, specialized –Simple means of circulation/distribution of materials throughout body –Storage place for waste products to be discharged to outside –Hydrostatic skeleton Fluid enclosed by muscular wall  support

14. Organ systems present: –Digestive system –Excretory system –Nervous system –Reproductive system Organ systems absent: –Circulatory system –Respiratory system Pseudocoelomates

15. Phylum Rotifera

16. Phylum Rotifera (non Molting) http://www.microscopyu.com/galleries/dxm1200/images/collothecalarge.jpg –rota= wheel (wave of beating cilia) –fera= bearer Freshwater, some marine B/w grains of sand Ciliated crown (corona) –Food, locomotion –(movie)(movie)

17. Phylum Rotifera http://micro.magnet.fsu.edu/primer/techniques/phasegallery/images/rotifer.jpg Mostly microscopic 1800 species Many resistant to desiccation dioecious

18. Phylum Rotifera Internal Anatomy of a Typical Rotifer Brain Muscular pharynx- mastax Protonephridia with flame cells Pedal glands

19. Phylum Nematoda The roundworms

20. Phylum Nematoda (Molt) 16,000 species –500,000 possible Cylindrical body (vermiform) Excretory system -renette Mostly dioecious Only longitudinal muscles –Undulate/thrash around (don’t crawl) moviemovie

21. Phylum Nematoda Noncellular cuticle with several layers –Primary layers of cuticle- cortex, matrix layer and basal layer –Maintains internal hydrostatic pressure –Provides mechanical protection –Resists digestion by host (in parasitic nematodes)

22. Phylum Nematoda (cont’d) Found everywhere –Oceans (free living and parasitic) –Polar ice –Hot springs –Soil Some play an important role in nutrient recycling

23. 5 billion per acre

24. Phylum Nematoda (cont’d) Eat just about every type of organic material –Rotting substance –Living tissue Parasites of nearly all plant and animal species!

25. Do these questions now… What type of germ layer lines the pseudocoelom in nematode embryos? What organ systems are present/absent in pseudocoelomates What are the advantages of having a pseudocoelom vs. no coelom?

26. Ascaris lumbricoides Human parasite –Up to 30cm long 1.2 billion people –Many in southeast US Females lay 200,000 eggs a day Unsanitary habits contaminate ground –Ingest eggs –Hatch  bury into veins  lungs  pharynx –Swallowed  intestine

28. Figure 11.10 Life cycle of Ascaris lumbicoides Molt Migrate to

29. Pinworms Most common parasite in US 30% children; 16% adults Large intestine Lay eggs (first-stage larva) in perianal area at night Itch and Spread –Fecal oral route –Larval molt four times in Small Intestines and migrate to large Intestines

30. Figure 11.11 Pinworm life cycle

31. Figure 11.13 (a) Trinchinella spiralis: the Porkworm

32. Figure 11.13 (b) Cyst Larvae in skeletal muscle

33. Filarial Worms “Elephantiatis” 250 million people (tropics) Lives in lymphatic system Obstruct lymph to cause swelling Microfilaria of Wuchereria bancrofti

34. Figure 11.15 Wuchereria spp. : Filarial worms Causes Elephantiasis

35. Other parasitic nematodes Hookworms Dog heartworms Trichinella (causes trichinosis)

36. biomedical research –C. elegans

37. C. elegans Free living nematode 959 cells –Development of every cell is known (movie)(movie) Genome sequenced –NCBINCBI

38. http://www.nobel.se/medicine/laureates/2002/press.html Sydney Brenner - C. elegans since 1963 C. elegans –Nobel Prize (2002) Brenner, Sulston and Horvitz –“Genetic regulation of organ development and programmed cell death”

39. Nematode-destroying fungi http://www.uoguelph.ca/~gbarron/N-D%20Fungi/n-dfungi.htm