Chapter 8 Flashcards
(32 cards)
What are the physical characteristics of Platyhelminthes
- dorso-vental flattening
- bilateral symmetry
- no coelom
- no anus
- no circulatory system
- flame cells or protonephridia
What are the 5 classes of playhelminthes
Turbellaria- free living, some parastitic
Monogenea- all ectoparasites
Aspidogastrea- parasites of fish, turtles and mollusks
Digenea- endoparasites
Cestodes- endoparasites (tapeworms)
What are the group are they part of and where in body are they found-Degeneans
part of Trematoda, in gut or offshoots (bile duct, lungs or bladder)
What are the physical characteristics of Degenean adults
oral sucker around anterior mouth for feeding
larger ventral sucker for attachment and locomotion
tegument
Explain what tegument is
naked protoplasmic layer with nuclei that sink into parenchyma
How do Degeneans eat
get nutrients from tegument and gut, site of amino acid and glucose uptake
What are the parts of the excretory system in Degeneans
flame cells, use osmoregulation
Explain how flame cells work
have a single central duct and an excretory pore at the end,
What type of sexual structure to Degeneans have
schistosomes and didymozadae- dioecious (seperate M and F)
all others are monoecious (both sexes)
What are the characteristics of the ootypes of Degeneans
it forms an eggshell, mehlis gland produces lipoprotein
Would Degeneans rather self fertilize?
it is possible but not preferred because of genetic diversity.
Explain a fluke’s life cycle from egg to miracidium
eggs pass from vertebrate host in feces or urine, zygote develops and forms a miracidium
Where in the Fluke’s life cycle does reproduction occur (in terms of what host)
asexual reproduction in mollusc, sexual reproduction in vertebrate
Map out the full fluke life cycle
slide 14
Describe a flukes life cycle in steps
- unembryonated eggs pass in feces of host (human or animal)
- embryonated eggs in water
- miracidia watch in water and penetrate snail
- in snail miracidia turns to sporocyst turns to rediae turns to cercariae,
- Free swimming cercariae leaves snail and is left in water or plants in water.
- human ingests metacercariae
- excystation in duodenum of human
- Adults form in SI, reproduce and form eggs, start over
Explain how flukes go from miracidium to sporocysts
miracidium infects snail, penetrates or is ingested, egg hatches in gut and miracidium penetrates further, looses cilia and becomes sporocyst
Explain how flukes go from sporocysts to rediae
sporocysts accumulate into germ balls. clone themselves and become redia, or stay sporocysts, migrate to digestive gland,
Explain how flukes go from redia to metacercariae
redia become cercariae with tail, leave snail and infect final host, penetrate skin and become metacercariae
What are metacercariae
encysted minature flukes, attach to vegetation or muscle of host
How are flukes specific
specific towards molluscan host, not as specific towards vertebrate hosts.
What fluke cercariae penetrates skin directly
schistosoma
What are the three classes of metacercariae
- develop on vegetation or surface of shells. infective once cyst forms
- need several days to become infective, do not grow in intermediate host
- need weeks of growth and differentiation before becoming dormant in 2nd host
How are types 2 and 3 metacercariae special
cysts that can take nutrients from second host, viable for up to 7 years
Why is the metacercaria stage important
allow for transmission to definitive host even if is doesnt feed on any organisms, attacks herbivores. can cross environments
