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Phylum Platyhelminthes

http://courses.bio.indiana.edu/S318-Lively/S318/lectureii/invert%20cladogra.gif

Flatworms are simple bilateral animals. • Flatworms have a solid body and incomplete or absent gut.

• There are three classes of flatworms.

– planarians

head

pharynx

mouth

sucker

eyespot reproductivesystem

gut cavity

• Flukes

– Tapeworms

CHARACTERISITCS OF ALL WORMS

InvertebrateElongated bodies

Bilateral symmetryCephalization

Cerebral ganglia “brain”No respiratory organs

(Breathe through skin)

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FLATWORMSPHYLUM: Platyhelminthes

FREE LIVING PARASITIC

Planaria Flukes & Tapeworms

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Phylum Platyhelminthes

• Flat worms• Acoelomate• Bilateral symmetry• Hermaphroditic

– Monoecious

• One opening for digestive system

• Paired lateral nerve cords & cerebral ganlion

• Flame cells

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Class Turbellaria

• Eye spots

• Ciliated surface

• Regenerate if cut in two

• Most are free-living

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Phylum Platyhelminthes: Class Turbellaria

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Acoelomate

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Turbellaria

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Nervous System

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BrainBrain

AuricleAuricle

Cerebral Cerebral ganglionganglion

PairedPairednerve cordsnerve cords

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Excretory System

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Class Trematoda

• Flukes• Parasites• Holdfast devices

– Most• Complex life cycle• Intermediate host

– Animal with juvenile stage• Definitive host

– Animal with adult stage

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Clonorchis sinensis

• Chinese liver fluke• 50 million people• Cirrhosis of liver• Diarrhea• Edema• Pain

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Clonorchis sinensis

Oral sucker

Intestine

Uterus

Yolk gland

Testes

Ovary

Seminal recepticle

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Fascioloa hepatica

• Sheep liver fluke• Sheep, cattle and

man– Weight loss

• Eat vegetation with metacercaria

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Life Cycle of the Sheep Liver Fluke

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Fasciolopsis buski

• Intestinal fluke• 10 million people• Man and pigs• Hemorrhage and

abscesses of small intestine

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Paragonimus westermani

• Lung fluke• Carnivores, pigs,

rodents and man• May be fatal

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Schistosoma

• Blood flukes• 200 million people• 1 million deaths/year

PARASITIC FLATWORMSchistosoma

Worms can block blood vessels to organs causing irritation, bleeding, tissue decay producing disease called = SCHISTOSOMIASIS

NOT IN USA but infects over 250 million people worldwide

http://www.coc.org/focus/food/pics/rice_paddy.jpg30

HUMAN BLOOD FLUKESchistosoma

Larva hatches from

egg & infects snail(intermediate host)

Eggs leave body in urine or feces

Adult worms mature & reproduce in blood vessels; eggs travel to intestines or bladder

Larvae grow tails and leave snail

Immature worms burrow through skininto blood vessels

http://www.biosci.ohio-state.edu/~parasite/lifecycles/schistosoma_lifecycle.gif

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Schistosome

• Cercaria have forked tail

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Swimmers Itch

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Class Monogenea

• One host• Ectoparasites

– Mainly fish• Opisthaptor

– Attachment to host

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Class Cestoidea

• Tape worms• No digestive system• 40 feet long

TAPEWORMS

PARASITIC FLATWORM that lives in HOST animal intestines

Dog tapeworm

http://www.bangkokhealth.com/cimages/tapeworm02.jpg

http://www.biosci.ohio-state.edu/~parasite/pictures/whole_tapeworms.GIF

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SCOLEX - Head with suckers and hooks to help hold on inside host

http://www.nicksnowden.net/images/Taenia_scolex_drawing.gif

ScolexScolex

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• PROGLOTTIDS hermaphroditic reproductive structures

• (contain both male & female sex organs)

Containfertilized eggs

Shed in feces

http://www.biosci.ohio-state.edu/~parasite/labeled_taenia.html

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Proglottid

UterusUterus

TestesTestes

OvaryOvary

Yolk glandYolk gland

Vas deferensVas deferens

Seminal receptacleSeminal receptacle

• TEGUMENT• Thickened PROTECTIVE layer

on the outside of worms made of CELLS

• CUTICLE• NON-CELLULAR PROTECTIVE

coating found on the outside of worms

http://www.nicksnowden.net/images/Taenia_scolex_drawing.gif

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TAPEWORM

• NO DIGESTIVE SYSTEM– absorbs nutrients through skin

• TEGUMENT protects them from host digestive enzymes and immune system

http://curezone.com/image_gallery/parasites/all/default.asp?i=66&n=75

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TAPEWORMS

• Can grow up to 30 ft – (2000 proglottids)

• REPRODUCE WITH PROGLOTTIDS– Add new proglottids behind scolex – Mature ones drop off at tail end – Leave body in feces

http://curezone.com/image_gallery/parasites/all/default.asp?i=65&n=75

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• MCDOUGALL VIDEO – CH.14 PREDATOR PREY 2 - TAPEWORM

EX: BEEF TAPEWORM

Adults attachinside intestinesand absorbdigested food

Proglottids arereleased in feces

Proglottids burst releasing eggs with larvae inside on ground

Cows eat grass; larvae travel through blood vessels;make cysts in muscle

Humans eat undercooked meatcontaining cysts

http://net.unl.edu/wonderwise/12parasi/a-para.htm46

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Pork Tapeworm (Taenia solium)

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Taenia saginata

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Source: Redrawn From Centers for Disease Control, Atlanta, GA.

Life Cycle of the Broad Fish Tapeworm

Diphyllobothrium latum

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Dipylidium caninum

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Echinococcus granulosus

• Parasite of dogs

– Host

• Juveniles in sheep, man and other mammals

– Intermediate host

• Hydatid cyst

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Hydatid Cyst

• Cysticercus – Juvenile stage

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