PHYLUM PLATYHELMINTHES

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PHYLUM PLATYHELMINTHES

• FLAT BODIED WORMS

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EXAMPLES

• PLANARIA FREE LIVING AQUATIC AND TERRESTRIAL
• Herbivore, carnivore, scavenger
• TAPEWORMS INTESTINAL PARASITE W/ MORE THAN 1
  HOST TAENIA
• FLUKES INTERNAL PARASITE W/MORE THAN ONE HOST
• BLOOD FLUKE SCHISTOSOMA
• LIVER FLUKE FASCIOLA

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Figure 25.15Page 424
b A definitive host eats infected, undercooked
beef
a Larvae become encysted in intermediate host
tissues
c Scolex of larva attaches to intestines wall
d Many proglottids form by budding
f Cattle may ingest embryonated eggs or ripe
proglottids to become intermediate hosts
e Ripe proglottids containing fertilized eggs
leave host in feces
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Figure 25.14Page 424
 Life cycle of Schistosoma japonicum
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TRAITS

• ORGAN LEVEL OF ORGANIZATION
• BILATERAL SYMMETRY
• SAC TYPE BODY 1 OPENING
• GASTROVASCULAR CAVITY IS BRANCHED
• TRIPLOBLASTIC 3 GERM LAYERS
• CEPHALIZATION
• BRAIN WITH 2 NERVE CORDS TRANSVERSE NERVES
• SENSE ORGANS

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TRAITS

• ACOELOMATE
• DIFFUSION METHODS FOR
• GAS EXCHANGE
• WASTE REMOVAL FLAME CELLS
• CIRCULATION
• REMEMBER DIFFUSION IS A SLOW PROCESS HI TO LO

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TRAITS

• MUSCLES FOR LOCOMOTION
• REPRODUCTION
• ASEXUAL REGENERATE
• SEXUAL HERMAPHRODITES BUT CROSS FERTILIZE

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Figure 25.4aPage 417
epidermis
gut cavity
no body cavity region between gut and body wall
packed with organs
Acoelomate organism (flatworm)
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Fig. 25.11a,bPage 422
pharynx (protruded)
protonephridia
flame cell
nucleus
cilia
fluid filters through membrane folds
opening of tubule at body surface
flame cell
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Fig. 25.11c,dPage 422
brain
nerve cord
genital pore
testis
penis
oviduct
ovary
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EVOLUTIONARY MILESTONE

• ORGAN LEVEL OF ORGANIZATION
• BILATERAL SYMMETRY
• CEPHALIZATION