Phylum PlatyhelminthesPhylum Platyhelminthes“Flat Worms”“Flat Worms”

By By Mr. “Super Bowl Bound” Mr. “Super Bowl Bound”

ChapmanChapman

PlatyhelminthesPlatyhelminthes

Platy = flatPlaty = flat

Helminthes = wormHelminthes = worm

Flat WormsFlat Worms

CharacteristicCharacteristicss 1. Triploblastic1. Triploblastic Three layers of cellsThree layers of cells

PlatyhelminthesPlatyhelminthesFlatworms 3 cell layers:Flatworms 3 cell layers:Ectoderm (epidermis)Ectoderm (epidermis)MesodermMesodermEndodermEndoderm

CharacteristicsCharacteristics 2. Linear nervous system with a ganglion 2. Linear nervous system with a ganglion

(brain)(brain)

CharacteristicsCharacteristics 3. Dorsoventrally flat, bilaterally symmetrical 3. Dorsoventrally flat, bilaterally symmetrical

bodybody

CharacteristicsCharacteristics 4. 4. CephalizationCephalization – the development of an – the development of an

anterior end (head)anterior end (head)

CharacteristicsCharacteristics 5. Incomplete digestive system (one 5. Incomplete digestive system (one

opening)opening) 6. An excretory system for removing cellular 6. An excretory system for removing cellular

wasteswastes

There are four classes of flatworms, three of which are important to us…

PlatyhelminthesPlatyhelminthes Class: Turbellaria – planaria and ribbon

worms.

Class: Cestoda – tapeworms

Class: Trematoda – flukes

The End