Endoparasites Overview Flashcards
(47 cards)
What are the common names for nematodes, cestodes, trematodes, and acanthocephalans?
- nematodes = roundworms
- cestodes = tapeworms
- trematodes = flukes
- acanthocephalans = parasitic worms
What is the general morphology of nematodes?
long and thin, unsegmented, circular in cross section
T/F? Nematodes are dioecious.
True! They have 2 sexes. (males = 2 spicules)
What are the 2 internal structures within nematodes?
GI tract + Reproductive tract
How would you describe the mouths of nematodes?
variable, with little bumps (papillae) and teeth
What are the 4 types of eggs that nematodes lay? How would you describe each?
- ascarid (round w/ thick outer shell)
- strongyle / trichostrongyle (oval + elliptical w/ thin shell, morula within)
- spiruroid (oval + rectangular w/ thin shell)
- trichuroid (elliptical w/ polar plugs)
What are the differences between direct life cycles vs. indirect life cycles?
- direct = no int. host, lives out entire life cycle
- indirect = int. hosts, can go from host to host
Where do you typically find the L1, L2, L3 stages of nematodes?
external environment + within int. hosts
Where do you typically find the L4, L5 stages of nematodes?
within def. hosts
What are some examples of nematodes commonly found in animals?
heartworms, hookworms, whipworms, threadworms
What are the two types/subclasses of cestodes?
- Cotyloda (psuedotapeworms)
- Eucestodes (true tapeworms)
What is the general morphology cestodes?
dorsoventrally flattened (ribbon-like) + segmented, in various sizes
What are the body + segments of a tapeworm called?
Strobilia (body) + Proglottids (segments)
T/F? Cestodes are dioecious.
False! They are hermaphroditic; each segment is considered male AND female.
How would you describe a tapeworm’s digestive system?
They do NOT have a GI tract; they absorb nutrients from the intestine of its host.
How would you describe a tapeworm’s reproductive tract?
- Each proglottid is hermaphroditic & has a reproductive tract
- frontmost segments = immature; middle segments = mature/reproducing; furthest back = gravid, with uterus.
In regard to tapeworms, what is the relevance of the word “hexacanth?”
refers to the larval stage with 6 hooklets
What are the 4 types of eggs that cestodes have? And how would you briefly describe them?
- pyriform apparatus (inner pear shape)
- dipylidium (multi hexacanths)
- taenia (wide shell, thick covering)
- psuedophylidean (operculated egg)
What is the main difference in how cotyloda tapeworms lay eggs vs. how eucestodes lay eggs?
- cotyloda pass one egg at a time
- eucestodes pass proglottids laying thousands of eggs at a time
What happens when a psuedotapeworm’s eggs make contact with water?
They hatch and become coracidiums
What are the usual hosts of psuedotapeworms?
- 1st int. host = copepod
- 2nd int. host = fish
- 3rd def. host = mammals, birds, reptiles
What are the proper names for each larval stage of psuedotapeworms?
- coracidium (after egg hatches)
- procercoid (eaten by copepod)
- plerocercoid (eaten by fish)
Which animals are the hosts of eucestodes?
- int. host = fleas
- def. hosts = cats, dogs, humans
How does the larva of a eucestode survive within its int. host?
It “encysts” within the int. host, in the form of a hydatid cyst.
