LABORATORIO: Parte 1 Filo Platyhelminthes

1. LABORATORIO: Parte 1Filo Platyhelminthes EJERCICIO 9

2. Goals for today • Learn to recognized the Phylum Platyhelminthes from other animals • Learn the main ‘diagnostic’ characteristics • Learn about some free-living and parasitic species biology

3. Platyhelminthes: flatworms These are acoelomate metazoans Lophotrochozoa More organized than radiate animals in that: • Bilateral symmetry (distinct head and sense organs, which allows direct movement). • Third germ layer-mesoderm (triploblastic animals) • Excretory system made up of specialized flame cells and tubules for removal of nitrogenous waste • Highly organized nervous and sense organs in the anterior part of the body (cephalization) Rotifera Porifera Annelida Mollusca Ecdysozoa Lophophorata Deuterostomia Platyhelminthes Cnidaria and Ctenophora Lophotrochozoa Protostomia Radiata Bilateria Parazoa Eumetazoa

4. Platyhelminthes: Classification Classes: Monogenea: don’t have material Turbellaria: • Ciliated epidermis • Paraphyletic group • Mostly free-living Cestoda: • Syncytial tegument without cilia • Long ribbon like body shape • Body divided in proglotids • Organs to attach host in the oral part of the body: suckers, hooks • No digestive system • Parasitic in digestive tract of all classes of vertebrates Trematoda: • Digenetic flukes • Syncytial tegument without cilia • Leaflike to cylindrical shape. • Organs to attach host in the oral and ventral part of the body: suckers, NO hooks • Parasitic in all classes of vertebrates

5. Platyhelminthes: Your Tasks Exercise 9A: • Phylum: Platyhelminthes • Class Turbellaria • Genus: Dugesia Planarias are freshwater usually under stones or submerged leaves or sticks. But other members of the class are marine

6. Platyhelminthes: Dugesia 1. Take a slide from your box with a planaria: identify the eyespot, aurículas, intestino, faringe, y boca. intestino boca What is the function of the eyespot and the auricles? ____________ Check your book for answers!

7. Platyhelminthes: Dugesia As in cnidarians the digestive tract of turbellarians is a gastrovascular cavity, the branches of which fill most of the body. They don’t have an anus so undigested food is ejected through the mouth! Yikes 

8. Platyhelminthes: Dugesia Reproduction: these animals are monoecious (hermaphrodites) they can reproduce sexually and asexually by transverse fission In asexual reproduction, the planarian detaches its tail end and each half regrows the lost parts by regeneration, allowing neoblasts(adult stem cells) to divide and differentiate. However, several problems can occur with this, so this does not happen often. In sexual reproduction, each planarian transports its excretion to the other planarian, giving and receiving sperm. Eggs develop inside the body and are shed in capsules. Weeks later, the eggs hatch and grow into adults. Sexual reproduction is desirable because it enhances the survival of the species by increasing the level of genetic diversity. wikipedia http://www.youtube.com/watch?NR=1&v=8mXkSdIpFQ8

9. Platyhelminthes: Dugesia Excretion and osmorregulation: the excretory system consist of canals and protonephridia called flamed cells. See these cells in action! http://www.youtube.com/watch?v=Rb_3KIB4CmE

10. Platyhelminthes: Dugesia 2. Take a slide from your box with a planaria cross section cuts: identify intestino, diverticulos intestinal, lumen de la faringe, musculos dorsoventrales.

11. Planaria – cross section circular muscle rhabdites longitudinal muscle epidermis intestine mesenchyme lumen of pharynx pharyngeal pouch pharynx

12. Platyhelminthes: Dugesia 3. Observe live planarias. Take a look to their locomotion. How does it use the head and auricles? Does it ever move backwards? http://www.youtube.com/watch?v=VplYBDSbRmA

13. Platyhelminthes: Dugesia 4. Observe live planarias. Perform with your instructor the stimuli experiments described in page 136. • Response to touch • Response to food • Response to directional illumination Write your answers this is part of the Planaria report

14. Platyhelminthes: Dugesia 5. Regeneration Experiment: Some planarians exhibit an extraordinary ability to regenerate lost body parts. For example, a planarian split lengthwise or crosswise will regenerate into two separate individuals When a planaria’s head is cut off, the remaining tail section will first regenerate a head. Even if the cut is made very close to the tail, the small tail section first regenerates the head and then continues to regenerate the rest of the tissue between the head and the tail. We will use this property and compare how long it takes for worms cut in different places to regenerate a head. If different parts of the planaria body have equal ability to regenerate, they should all regenerate the head in the same amount of time. If not, they should regenerate the head in different amounts of time. The regenerative capacity of different body sections may be an indicator of the location of stem cells called neoblasts. For instance, if one body segment has a low capacity to regenerate, perhaps only a few neoblasts exist in the area around the cut. Additional neoblasts may need to migrate to the area or be created by cell division, slowing down the rate of regeneration. http://www.youtube.com/watch?NR=1&v=gZmk80fw0nc

15. Platyhelminthes: Your Tasks Exercise 9B: • Phylum: Platyhelminthes • Class Trematoda • Genus: Clonorchis sinensis Clonorchis lives in the human bile duct (bilis) where it feeds on bile and lacerated cells from the inflamed bile duct very common in Asia

16. Platyhelminthes: Clonorchis 1. Observe slide of Clonorchis sinensis: identificar ventosa oral, boca, faringe, intestino, ventosa ventral, glandula de yema, poro genital, vesicula semina, ovario, receptabulo seminal, testículos, vejiga, poro excretor

17. Platyhelminthes: Your Tasks Exercise 9B: • Phylum: Platyhelminthes • Class Trematoda • Genus: Schistosoma mansoni Schistosoma are blood flukes of humans that affect ~ 200 million people in Asia, Africa, the Caribbean (including Puerto Rico!) and South America. Schistosomiasis

18. Platyhelminthes: Schistosoma 1. Ciclo de vida: Observe slides of Schistosoma mansoni adults, eggs, and cercariae eggs miracidum cercariae You need to understand the life cycle adults

19. Platyhelminthes: Your Tasks Exercise 9C: • Phylum: Platyhelminthes • Class Cestoda • Genus: Taenia pisiformis- dog tapeworm They are extreme parasites in that they don’t have a digestive system. Their tegument is a specialized epidermis that absorbs nutrients and rejects toxins and digestive enzymes. Live is all about maximize reproduction. In fact tapeworms are egg factories, some species can even fertilize their own eggs an strategy that guarantees offspring.

20. Platyhelminthes: Taenia 1. Observe slide of Taenia. Noticed the scolex and the body composed of units called proglottids which are not segments, but units formed by budding behind the scolex. Scolex proglottids

21. Platyhelminthes: Taenia 1. Observe slide and model of Taenia scolex which is equipped with suckers and hooks. Note the neck from which new proglotids are budded off. A= suckers B=hooks scolex

22. Platyhelminthes: Taenia 2. Observe slide and model of Taenia mature proglotid. They have reproductive organs: testículos, vaso deferente, poro genital, glandula de yema, ovario, vagina, utero, cordon nervioso, canales excretores.

23. Uterus

24. Platyhelminthes: Taenia 2. Observe slide and model of of Taenia gravid proglottid, with the uterus fulled with eggs or embryos. Where do you find gravid proglottids? These proglottids break off and shed in the feces of the host. Outside the host the proglottid breaks releasing thousands of infected eggs. Uterus with eggs

26. Platyhelminthes: Taenia Taenia life cycle

27. Important Links Platyhelminthes http://www.savalli.us/BIO385/Diversity/05.Platyhelminthes.html http://es.wikipedia.org/wiki/Platyhelminthes http://www.pbs.org/kcet/shapeoflife/episodes/hunter.html