lecture 4 Flashcards
what are parasitic helminths?
parasitic worm-like organisms that live in and feed off living hosts
are helminths endoparasites or ectoparasites?
endoparasites
where do helminths live as sexually mature adults?
the GI tract
how do helminths injure their host? (2 ways)
mechanically and chemically
what are the three groups of helminths?
- cestodes
- trematodes
- nematodes
for the _____, each proglottid segment of the adult tapeworm is hermaphroditic
cestodes
all _____ are hermaphrodites, except for the schistosomes
trematodes
adult parasitic _____ have separate male and female worms
nematodes
platyhelminths are flatworms because most are ________
dorsoventrally flattened
what are the two classes of Phylum Platyhelminthes?
- Class Cestoda - Tapeworms
2. Class Trematoda - Flukes
what are the two subclasses of class cestoda?
- subclass cestodaria
2. subclass eucestoda
what are the two orders of subclass eucestoda?
- order cyclophyllidea
2. order pseudophyllidea
cestodes lack a ____ & a _____
mouth & a digestive tract
what is the life cycle of a tapeworm?
the adult tapeworms live in the definitive host (predator) while the prey plays host to the intermediate stages. o Eggs laid by the adult pass out in the feces of the definitive host and are eaten by the intermediate host. o These develop into the intermediate stage, which generates the adult when eaten by the definitive host. o A tapeworm may pass through several intermediate hosts before it finds the right definitive host
what are the intermediate hosts of tapeworms?
- a mammal
- an arthropod
- a fish
- a bird
- a reptile