1 Phylum Platyhelminthes. 2 Flatworms Triploblastic Acoelomate Bilateral symmetry Hermaphroditic...
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Transcript of 1 Phylum Platyhelminthes. 2 Flatworms Triploblastic Acoelomate Bilateral symmetry Hermaphroditic...
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Phylum Platyhelminthes• Flatworms• Triploblastic• Acoelomate• Bilateral symmetry• Hermaphroditic (Most)
– Monoecious
• One opening for digestive system - incomplete gut
• Paired lateral nerve cords & cerebral ganglion
• Flame cells - modified excretory cells
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Nervous System
Lateral nerve cordLateral nerve cord
ConnectivesConnectives
AuricleAuricleEye spotEye spot
Cerebral ganglionCerebral ganglion
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Excretory System
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Class Turbellaria• Eye spots - Ocelli• Ciliated surface• Dual Adhesion Glands -
to attach and release• Regenerate if cut• Most are free-living• Detect food by
chemoreceptors• Detect Water Current -
statocysts• Sexual Reproduction:
– Internal Fertilization– Cocoon attached to plants
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Turbellaria
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Class Trematoda
• Flukes• Parasites - endoparasitic• Holdfast devices
– Hooks and Suckers
• Complex life cycle• Intermediate host
– Animal with juvenile stage
• Definitive host– Animal with adult stage
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General Trematoda (FLUKE) Life Cycle General Trematoda (FLUKE) Life Cycle Egg passes from definitive host and must Egg passes from definitive host and must reach waterreach waterHatches into a free-swimming ciliated Hatches into a free-swimming ciliated larva, the larva, the miracidiummiracidiumMiracidium penetrates tissues of a snailMiracidium penetrates tissues of a snail
Transforms into a Transforms into a sporocystsporocystSporocyst reproduces asexually to form Sporocyst reproduces asexually to form rediarediaRediae reproduce asexually and form Rediae reproduce asexually and form cercariacercariaCercaria attach to fish and form cysts in Cercaria attach to fish and form cysts in muscle tissuemuscle tissue
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Schistosoma
• Blood flukes/Liver• 200 million people
infected• 1 million deaths/year• Sexes are separate• Pierce through Skin
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Life Cycle of a Schistosome Fluke
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Cut Liver of individual who dies from hematemesis
(vomiting blood). 180 adult blood flukes were found in autopsy
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Schistosome
• Swimmers Itch - Schistosoma Dermatitis– Cercaria penetrate
wrong host– skin becomes irritated
and inflammed = itch
Cercaria have forked tail
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Class Cestoidea
• Tape worms• No digestive system• 40 feet long• Individual units =
proglottids– Contain own reproductive
structures and organs
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Proglottid
UterusUterus
TestesTestes
OvaryOvary
Yolk glandYolk gland
Vas deferensVas deferens
Seminal receptacleSeminal receptacle
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Pork Tapeworm (Taenia solium)