phylum nematoda Flashcards
two groups of protostomes
lophotrochozoa and ecdysozoa
characteristics of ecdysozoa (2):
- periodically moult exoskeleton
2. no motile cilia or flagella
nematodes only have ____ muscles
longitudinal
nematodes grow by:
the enlargement of cell size
eutely - fixed number of cells
cilia (aberrant) of nematodes are restricted to:
seonsory structures
why is the intestine of nematodes collapsed?
because of the high pressure pseudocoel
movement in nematodes occurs because of (3):
- stiff cuticle - resists tension
- high pressure fluid filled pseudocoel
- longitudinal muscles only
feeding in nematodes
sucking by triradiate muscular pharynx
- myoepithelial cells contract, lumen opens and food/fluid is drawn in
asexual reproduction in nematodes occurs by:
parthenogenesis (very few species)
sexual reproduction in nematodes:
most are dioecious
- internal fertilization - males have copulatory spicules, aflagellate ameboid sperm
how many moults do nematodes undergo
4
facultative diapause occurs in:
dauer larva
facultative diapause occurs after larval stage __ and is triggered by ____
two; environmental cues
in facultative diapause, when conditions improve, the larva moults to larval stage ___
four; skips larval stage 3
hookworm (parasitic nematode) has how many hosts?
one - human
life cycle of hookworms
eggs passed in feces, moist soil, human with bare feet in moist soil – penetrates skin, travels to heart, lung - alveoli , then into intestine of human host
hookworms use teeth elaborated from ___ to grab onto the wall of the small intestine
cuticle
the parasitic nematode wuchereria bancrofti causes which disease?
elephatiasis (lymphatic filariasis)
- clogging of lymphatic vessels
the parasitic nematode wuchereria bancrofti has how many hosts?
2 hosts: human and mosquito
parasitic nematode - golden nematode has how many hosts?
one host - potato
what are the ‘cysts’ on roots of potatoes infected by the golden nematode?
dead,swollen bodies of females filled with eggs
caenorhabditis elegans is a model organism for:
developmental genetics
