5: Nematoda Flashcards
- large superphylum that includes: nematodes, tardigrades, arthropods
- characterized by presence of cuticle
- no common body plan
ecdysozoa
tough but flexible exoskeleton that protects organism from external dangers
cuticle
how animals regularly molt the cuticle
ecdysis
- free living or parasitic
- inhabit nearly every habitat
- pseudocoelomate
- circular cross-section
nematode
- what nematode cuticle is made of
- secreted by epidermis
- shed throughout growth
collagen
cuticle contains the ____ _____ from fluid in the ____ and protects the worm from the external environment
hydrostatic pressure; pseudocoel
the fluid filled pseudocoel serves as ____ ____; hydrostatic pressure is higher in nematodes than in other animals w hydrostatic pressure
hydrostatic skeleton
nematodes only have a ____ ____ (whiplike movement)
longitudinal layer
the nerve chords in nematodes form this around the pharynx by fusing at the anterior end
pharyngeal nerve ring
how many longitudinal nerve cords do most nematodes have?
4
chemosensory organs found near the head
amphids
reduced amphids usually in parasitic nematodes; similar structures in posterior region
phasmids
most nematodes are (monoecious/dioecious?); fertilization is (internal/external?)
dioecious; internal
- transmission: soil
- life cycle: larvae in lungs –> throat –> adults in small intestine
- effects: abdominal symptoms, allergic reactions
Ascaris lumbriocoides
- transmission: juveniles burrow in skin
- life cycle: juveniles in intestine to feed on blood –> eggs in feces
- effects: anemia, stunt growth in children
- anterior end resembles a hook
hookworms
- transmission: consumption of raw meat w cysts release into intestine
- adult F produce young in small intestine –> juveniles penetrate blood vessels –> skeletal muscle cells= redirect gene expression
trichinellosis
in trichinellosis, the muscle cell loses its striations= becomes a ____ that provides nutrition to the worm
nurse cell
infects humans, hogs, rats, cats, dogs, other mammals; genus w number of species that causes trichinellosis
trichinella
- Enterobius vermicularis
- transmission: scratching itch in anal region contaminates hands, swallowed
- life cycle: eggs hatch in duodenum–>mature in S intestine–>adults L intestine –> lay eggs in anal region
pinworms
- filarial worm
- caused by Wuchereria bancrofti
- results in parts of body swelling severely
elephantiasis
- filarial worm
- frequent causes of disease in dogs
heart worms
