http://www.starfish.ch/Fotos/worms Wuermer/plathelminthes Plattwurm/Pseudobiceros-gloriosus3.jpg

Worms

http://georgiafaces.caes.uga

.edu/graphicsfiles/LandPlan arian33hr.jpg

http://neatorama.cachefly.net/images/ 2009-02/tapeworm-rhinebothrium.jpg

Phylum Platyhelminthes

• • • • • • “The Flatworms” (dorsoventrally flat) Triploblastic! (Organ systems seen) Mouth, but no anus Most monoecious More complex nervous system 4 Main Classes: – Turbellaria – Monogenea – Trematoda – Cestoidea

• Class Turbellaria: Free living Flatworms – Mostly bottom dwellers in water (fresh & marine) – Named for the “turbulence” of their beating cilia – Movement by layers of muscle cells and rhabdites (cells that form mucus) – Feeding by pharynx (mouth); mostly carnivorous – Respiration by diffusion through the body wall – Simple kidneys = protonephridia (with flame cells) – Simple brain = cerebral ganglia – 2 simple eyes = ocelli – Other sensory body parts: auricles on sides of head

Planaria

• Reproduction: – – Asexual (by transverse fission- producing zooids) Sexual (cross-fertilization- penis inserted; eggs laid sometimes in a cocoon) http://www.eeob.iastate.edu/ faculty/DrewesC/htdocs/plan aria-cocoonR.jpg

penis transverse fission

http://wpcontent.answers.com/ wikipedia/commons/thumb/3/38 /Flatworm_sex.png/200px Flatworm_sex.png

http://farm1.static.flickr.com/187/438039243_fccd05bd4f.jpg

Marine Turbellaria…

http://www.rzuser.uni heidelberg.de/~bu6/pow.jpg

•

Class Monogenea

– Mostly external parasites of freshwater and marine fishes (attach to gills) http://www.uen.org/utahlin k/tours/admin/tour/18753/ 18753monogenea.gif

http://www.sardi.sa.gov.au/__data/as sets/image/0007/84148/mp_Hexosto ma.gif

http://www.digsfish.com/imgs/finfish/figure%204.jpg

• Class Trematoda: Parasitic Flatworms-“Flukes” – Almost all are parasites of vertebrates – All have various body parts for attachment – Subclass Aspidogastrea: mollusc fluke • Opisthaptor = holdfast organ on entire ventral surface • NO oral sucker – Subclass Digenea: majority of flukes • 2 large suckers: oral sucker and acetabulum (below oral sucker) • May have multiple hosts (including humans)

http://www.nutridirect.co.uk/images/fluke.jpg

Subclass Digenea:

Subclass Aspidogastrea (ventral view)

http://parasitology.informatik.uni-wuerzburg.de/login/b/tn_me14236.png

• Popular Trematode Parasites of Humans: – Chinese liver fluke – Sheep liver fluke – Blood flukes

http://www.fao.org/docrep/008/y5970e/y5970e04.jpg

http://www.phsource.us/PH/HEL M/Helminth_images/Clonorchis %20sinensis.jpg

Chinese Liver Fluke:

picked up by humans who eat infected raw fish

http://images.wool.com/pub/liver_fluke_cycle.gif

Sheep Liver Fluke:

Picked up by humans who eat the freshwater plant watercress http://www.k state.edu/parasitology/625t utorials/FIGfasciola08.jpg

http://siera104.com/images/bio/flatroundrotifers/shistomsoma.jpg

Blood Flukes:

Attach to human skin from infected water source http://animal.discovery.com

/tv/a-list/creature countdowns/horrors/images /fluke-horrors.jpg

http://www.uen.org/utahlink/activities/uploads/7487_a_schistosoma_in_copula.gif

• Class Cestoidea: The Tapeworms – Most live in vertebrate digestive system – Adults lack pigment (white color) – Can grow to large lengths (up to 25 m) – No mouth or digestive tract (they absorb nutrient directly across body wall) – Nervous system not as complex as other platyhelminthes – Monoecious – Adults are made of repeating body units (proglottids- hold reproductive organs) – Subclass Cestodaria = no proglottids • Parasites of fishes

• Subclass Eucestoda: True Tapeworms – 3 body regions: • Scolex- anterior end with suckers and hooks • Neck- area of growing proglottids • Stobila- posterior area of proglottids ***proglottids closer to posterior are more mature

http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20102/Bio%20102%20lec tures/Animal%20Diversity/lower%20invertebrates/tapeworm1.jpg

http://farm2.static.flickr.com/1251/ 617427668_e747238c1a.jpg

• Popular Tapeworms Parasites of Humans: – Beef tapeworm – Pork tapeworm – Broad fish tapeworm

All ingested by infected meat