Phylum Nematoda Flashcards
general characteristic
“round worm” pseducoelom compète digestive track unsegmented reproduce sexually>separate sexes can be found anywhere free living or parasite but most are parasites
advantages over platyhelminthes
pseudocoelom
complete digestive track
evolutionary advances
reproduce sexually
classes and examples
trichinosis-undercooked pork filarial worms- causes elephantiasis ascaris- human intestine parasite hookworm- contaminated soil heart worms- dogs
Digestion and feeding
mouth and anus allows for continuous digestion of food
more efficient
waste removal does not interfere with food intake
digestion organ pathway
mouth-pharynx-intestine-anus
respiration system
no system all by diffusion
circulation (internal transport)
no system
fluid in pseudocoelom distributes digested nutrients and oxygen
excretion
excretory pores open to outside
similar to flat worms.
nervous system : response
simple system; several ganglia
nerves extend from the ganglia and run down the length of the body
sense cells detect chemical from prey or host
nervous system: movement
muscles extend length of body
fluid in coelom and muscles work to extend worm by hydrostatics
Asexual reproduction
NONE
sexual reproduction
separate sexes
internal fertilization
male deposits sperm in female reproductive tract
male worms have a “hook” on tail to assist with sperm transfer.
life cycle of ascaris in humans
- the eggs are in soil (unfertilized)
- the eggs become fertilized
- this infected larvae is ingested with food
- reached duodenum, penetrates the walls and goes into blood
- migrate to the lungs
- final development in the small bowel
