Phylum Platyhelminthes

1. Phylum Platyhelminthes Michael Xu & Patricia Cheng Period 6

2. General Characteristics • Mostly parasitic • They are acoelomates • Soft and ciliated epidermis, or covered with cuticle and with external suckers or hooks – used to attach to host • About 20,000 species found in marine and freshwater • Free living flat worms rely on camouflage. • Flatworm can be microscopic or many feet long and is generally very thin

3. Classes Monogenea [flukes] Turbellaria [free living flatworms] http://www.nhc.ed.ac.uk/images/collections/invertebrates/parasitic/LgMonogenea.jpg http://www.thaigoodview.com/library/contest2551/science04/119/kingdon_animalia/images/turbellaria4.jpg

4. Classes Continued Trematoda [flukes] Cestoda [tapeworms] http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20102/Bio%20102%20lectures/Animal%20Diversity/lower%20invertebrates/tapeworm1.jpg http://www.emc.maricopa.edu/faculty/farabee/BIOBK/01fluke.gif

5. Form & Function End Body Plan Click the boxes to navigate! Wait until you see your cursor before clicking… Respiration Feeding Circulation Reproduction Movement Excretion Response

6. Body Plan Click anywhere to return! • Bilateral Symmetry • Body has 3 layers of tissues with organs and organelles (triploblastic) • No internal cavity • Has a blind gut, mouth but no anus • Dorsoventrally flattened (hence, flatworms) • Cephalization, a specialization of the anterior end of the animal, can be seen in the clustering of sensory structures and clumps of nerves in the head region. • The mesoderm gives rise to muscles, various organ systems, and the parenchyma

7. Feeding Click anywhere to return! • Usually carnivorous, eating a wide range of living and dead organisms • Some species feed on algae • Mostly they feed on animals and other smaller life forms • Turbellarians have a muscular pharynx to up food. • Parasitic classes rely on the host for digestion. http://infusion.allconet.org/webquest/PhylumPlatyhelminthes.html

8. Respiration Click anywhere to return! • Respiration occurs through diffusion, on the cellular level • Being flat helps the diffusion • A flatworm takes in oxygen, but has no formal respiratory system. http://www.earthlife.net/inverts/platyhelminthes.html

9. Circulation Click anywhere to return! • Circulation occurs through diffusion. • No special organs for circulation, gut is only body cavity • The gut is often highly branched to allow for more effective transportation and diffusion of food to all parts of the body http://www.pbs.org/kcet/shapeoflife/animals/platyhelminthes.html

10. Excretion Click anywhere to return! • Incomplete digestive system, no anus, usually much branched • Excretory system consists of many flame cells connected to excretory ducts • A flatworm has a combination digestive/excretory system. • A flatworm gets rid of wastes through the same opening it takes in food. • Protonephridial excretory organs replace anus http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html

11. Response Click anywhere to return! • A flatworm has a very simple nervous system with two nerve cords running down either side. • It has two simple brains called ganglia, which are simple bundles of nerves. • It has two eyespots (ocelli) that help it sense light. • Some platyhelminthes have chemoreceptors, balance receptors, and receptors for water movement http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm

12. Movement Click anywhere to return! • Some groups, like turbellians, use cilia on the epidermis for locomotion on slime trails • Parasitic worms rely on the hosts circulatory system for transportation • Some species have longitudinal, circular, and oblique layers of muscle under the epidermis which help with movement http://www.discoverlife.org/20/q?search=Platyhelminthes

13. Reproduction Click anywhere to return! • Mostly sexual reproduction, as hermaphrodites • Reproductive system of each sex with gonads, ducts and accessory organs • Fertilization occurs internally • Lays strings of microscopic eggs each enclosed with several yolk cell in a shell • Development is either direct or with one or more larval stages • Asexual reproduction occurs through fragmentation or fission. http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm

14. Bibliography TEXT • "The Flatworms and Tapeworms (Phylum Platyhelminthes)." The Earth Life Web. Web. 20 Apr. 2010. <http://www.earthlife.net/inverts/platyhelminthes.html>. • "Introduction to the Platyhelminthes." UCMP - University of California Museum of Paleontology. Web. 20 Apr. 2010. <http://www.ucmp.berkeley.edu/platyhelminthes/platyhelminthes.html>. • "Platyhelminthes." W. Fielding Rubel School of Business: Bellarmine University. Web. 20 Apr. 2010. <http://cas.bellarmine.edu/tietjen/images/platyhelminthes.htm>. • Platyhelminthes." Oracle ThinkQuest Library. Web. 20 Apr. 2010. <http://library.thinkquest.org/26153/marine/platyhel.htm>. • "M31.htm." Meer Home Page. Web. 20 Apr. 2010. <http://www.meer.org/M31.htm>. • "The Shape of Life . Platyhelminthes." PBS. Web. 20 Apr. 2010. <http://www.pbs.org/kcet/shapeoflife/animals/platyhelminthes.html>. • "Flatworm." Monroe County Women's Disability Network. Web. 20 Apr. 2010. <http://www.mcwdn.org/Animals/Flatworm.html>. • "Phylum Platyhelminthes." Infusion. Web. 20 Apr. 2010. <http://infusion.allconet.org/webquest/PhylumPlatyhelminthes.html>. • "Animals - Phylum Platyhelminthes." Oracle ThinkQuest Library. Web. 20 Apr. 2010. <http://library.thinkquest.org/28751/review/animals/3.html>. PICTURE • "Platyhelminthes - Flatworms, Tapeworms, Flukes." Discover Life. Web. 20 Apr. 2010. <http://www.discoverlife.org/20/q?search=Platyhelminthes>. • สาระ ความรู้ ข่าวสาร ความบันเทิง ของชาวมัธยมศึกษา และประถมศึกษา : Knowledge for Thai Student | ThaiGoodView.com. Web. 20 Apr. 2010. <http://www.thaigoodview.com>. • Natural History Collections: Home. Web. 20 Apr. 2010. <http://www.nhc.ed.ac.uk>. • Estrella Mountain Community College. Web. 20 Apr. 2010. <http://www.emc.maricopa.edu>. • Clinton Community College. Web. 20 Apr. 2010. <http://faculty.clintoncc.suny.edu>.