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describe the basic features off a common platyhelminth
- unsegmented flatworms
- Acelomate (lack a coelom or body cavity) w/ parenchyma (spongy mesenchymal cells filling spaces betweem viscera, muscles or epithelia)
- tegument (living outer covering ; used to absorb stuff in parasites) of living cells
- incomplete gut or none at all
- protonephridia of flame cells
- no respiratory or circulatory systems
- monoecious= hermaphroditic
- ectolecithal eggs (yolk comes from outside the the egg) in parasitic and turbellarian species
- can't synthesize fatty acids or sterol de novo
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Distinguish between the two types of teguments
- Free living- block style
- - +/- cilia
- - duo- gland adhesive organs
- Parasitic - syncytial= a large cell-like structure filled with cytoplasm containing many nuclei. (neodermata)
- - this type of tegument is better at changing surface proteins and easier to repair
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what does duo-gland adhesive system mean and who has them?
- cells that produce adhesive secretions are paired with those that produce releasing secretions
- found in turbellarians and some free-living stages of cestoidea and trematoda
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What are the three types of Neodermata Platyhelminthes and what (if any) subclass are under them?
- 1. Trematoda
- -Aspidobothrea- transition forms, bivalve parasites
- -Digenea- 2 hosts, snail and vertabrates, known as "flukes"
- 2. Monogenea
- - ectoparasites, direct life cycle
- 3. Cestoidea
- - tapeworms
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Characteristics of Aspidobothrea
- direct life cycle= one host
- -parasites of bivalves
- ventral sucker(s)
- cotylocidium larva
- can live outside of host
- anatomy is digenea like
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Characteristics of Digenea
- AKA "flukes"
- indirect life cycle
- -1st host is snail (intermediate host)
- - 2nd host is vertebrate (definitive host)
- has multiple larvel stages
- several pathogenic
- second most common parasitic worm
- incomplete gut
- can reproduce sexually or self fertilize
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What are the three types of body forms found in Digenea?
- 1. Monostome- only oral sucker
- 2. Distome- oral and ventral sucker; most common3. Amphistome- ventral sucker at posterior margin
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generalized life cycle of class Digenea
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generalized life cycle of digenea explained
- adult fluke
- - hermaphrodite; in definitive host
- eggs
- - opurculate;ectolecthial; in feces
- miracidium
- - ciliated; free living, infects snails
- sporocyst
- - no mouth, germ balls, in snail
- redia
- - mouth, germ balls, in snail
- cercaria
- - fluke w/ a tail, free living
- metacercaria
- - encysted form, may be in third host
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Characterstics of class Monogenoidea
- trematode like morphology
- ectoparasite
- posterior attachment (opisthaptor) w/ suckers and hooks
- direct life cycle oncomiracidium larva
- Polyembryony- maintain multiple generations on the uterus, allows for the host to be infected by multiple generations
- not much pathology unless you have lots of them
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characteristics of class Cestoidea
- tapeworms
- pseudo-segmented aceolomates
- no respiratory, circulatory, or digestive systems
- indirect life cycle- predator/prey cycle
- - adults in gut, low pathology
- - metacestodes, pathogenic
- hexacanth embryos- 6 hooked embryo
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characteristics of Cestoidea adults
- scolex ("head" or holdfast organ) for attachment
- - +/- hooks and suckers
- neck is generative region
- strobila- body region of proglottids
- - each is functional hermaphrodite
- - mature proglottid- reproductively mature
- - gravid proglottid- means that it is holding eggs
- some monozotic- unsegmented
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