Ch 17: Nematoda and Nematophora Flashcards
nematoda are ? and ?
free-living, tiny
5 features of nematodes
- bilateral
- triploblastic
- complex cuticle
- direct development
- pseudocoelom
how many times does a nematode molt its cuticle?
4
what is the inter-molt stage called
an instar
how do nematodes grow?
mainly by increasing cell size rather than cell #
cuticle feat (2)
- fibrous
- up to 9 layers thick
what forms the hydrostatic skeleton in nematodes?
fluid under high pressure pushing against the cuticle
what does it mean to have a pseudocoelom
not lined on the outside by medoderm
what does the internal pres require the gut to be
muscular
pharyngeal pump funct
drawing in liquids
all muscles are
longitudinal
how many nerve cords and in what direction
4 longitudinal
renette
a glandular system in marine spp that excretes salt
4 sensory structures
- may detect light @ body wall
- some spp have ocelli
- touch via papillae and setae
- chemosensory pits/amphids
sexes
separate; males have hooked tail
cloaca in males
genital and anal opening
fert is
internal
nematode range
abundant EVERYWHERE in pretty much every climate
what do free-living nematodes eat (4)
- bacteria
- fungi
- other nematodes
- plants/crops
stab prey w/ (2)
- tooth-like mouth plates
- stylet (plants)
5 “pre-adaptations” for a parasitic lifestyle
- resistant cuticle
- microphagus
- small size
- r-selected
- internal fert
where do pin worms develop into adults and feed?
human gut/large intestine
how does pin worm reinfection occur?
scratching butt then putting hands in mouth - eggs laid near anus
hookworms feed on ? in ?
blood, hosts gut
at what stage do pinworms enter the host
eggs
at what stage do hookworms enter the host
larva penetrates skin or enters w/ food
how do hookworms enter the gut?
travel thru circ system until they enter the lungs and are coughed up, then re-swallowed back into the gut
guinea worm in skin
causes an ulcer and opening in the skin
how does the guinea worm complete its lifecycle
person goes to cool off in the w, then eggs are released
filarial nematodes features (2)
- thread-like
- vectored by biting flied (int host)
4 filarial nematodes
- elephantiasis
- whipworm
- river blindness
- canine heartworm
elephantiasis
blocking of the lymphatic vessels
whipworm
adults feed on blood in intestine
river blindness feat (2)
- young worms damage the eyes
- vectored by infected black flies
canine heartworm
vectored by mosquitoes
ascaris (3)
- large gut parasites
- spread through dogs or pigs
- migrating larva can damage organs
trichinella (2)
- tiny endoparasites
- burrowing of larvae can be fatal
2 useful tids about nematodes
- used in genetics
- biological insecticides
nematomorpha
horsehair worms
2 features of nematomorpha
- gut degenerated in adults
- 2 longitudinal nerve cords
adult is ? and ?
free-living, short lived
larvae functs (3)
- endoparasites of arthropods or leeches
- live in host and absorb nutrients
- enter hosts via stylets or hooks
nematomorpha cause insanity
driving hosts to drown themselves to complete their lifecycle
