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Description
Flashcards by Kirstin Latimer, updated more than 1 year ago
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Created by Kirstin Latimer
almost 9 years ago
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| Question | Answer |
| How is the phylum divided? | - Neodermata = Monogea, Digenea, and Cestoda - Turbellaria = flatworms |
| List the key body plan features of platyhelminthes. | - bilateral - triploblastic - acoelomate - unsegmented - no circulatory system - mouth and gut, no anus - anterior brain and nerve cords |
| Describe the structural and ecological features of Turbellaria. | - ciliated epidermis - free-living flatworms - freshwater, marine or moist terrestrial - each species has a food niche |
| Describe the origins of parasitism in Neodermata. | - began on vertebrate hosts - first ecto then endoparasites - use of secondary hosts evolved after divergence of trematodes and cestodes from monogea - T and C = highly evolved = alternation of generations and hosts |
| Describe the structural and ecological features of Monogea. | - ciliated larvae = oncomiracidia - well developed opisthaptor - swim to host attach and form neodermis - hosts = fish |
| Describe the structural features of Cestoda. What are the two divisions? | - scolex - strobila = body without hear and neck - made up of proglottids - do not have gut - Cestodarians - Eucestodes |
| Describe the life cycle of cestodes. | - eggs in faeces -> environment - cattle/pigs infected by vegetation - oncospheres hatch and penetrate intestinal wall -> muscle - develop into cysticerci - humans infected by meat |
| Describe the life cycle of Fascioliasis. | 1. unembryonated eggs in faeces 2. embryonate eggs in water 3. miracidia hatch, penetrate snail 4. different stages in snail 5. cercariae released from snail -> encyst on vegetation as metacercariae 6. ingested by mammals -> excyst in duodenum and migrate into biliary ducts |
| Describe the pathology of Schistosomiasis. | 1. sweet water snail 2. cercariae penetrate through pores, enter blood stream and develop into adult schistosomes 3. adults in liver migrate to digestive tract and mate, release eggs 4. eggs excreted in faeces/urine, hatch into miracidiae -> infect snail -> cercariae |
| What are acoels? | - primitive flatworms - unsure as to phylogeny - no longer platyhelminthes? |
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