phylym platyhelminthes Flashcards
general characteristics
flat
soft bodied
have tissue and internal organs
no body cavity
advanced over cnidaria
3 germ layers bilateral symmetry cephalization regeneration excretion with flame cells
classes and example
turbellaria- planaria(free living-freshwater)
flukes- liver fluke (parasites)
cestoda- tapeworm(parasite)
instead of a brain they have
ganglia (2 nerves together)
digestive organ pathway
pharynx>mouth>GVC>intestine>pharynx> mouth
what body plan?
“sac” single opening
what is the pharynx
it extends out of mouth and pumps foods into gut and intestine where digestion takes place
digestion for parasites?
they don’t need a digestive system
they obtain nutrients already digested
nutrients diffuse through “skin” of a flat worm from the host
cuticle?
protects tape worm from host digestive juices
respiration
flat… all sides exposed to air/water (diffusion)
circulation
no system
all by diffusion
worms are flat and have a high surface area
almost all cells are in direct contact with air
excretion
flame cells- specialized cells to remove excess water& waste from body
nervous system (response)
ganglia- group of nerves, simple, primitive “brain”
2 nerve cords; run down side of body(lateral)
eyespots- detect light
specialized cells throughout the body to detect chemicals in food or water
nervous system (movement)
cilia- helps them glide
muscle cells and tissue twist and turn
tape worm and parasites attach to host intestine and don’t move much
asexual reproduction
fission- splits in 2 & grows 2 new worms
breaks into pieces; each piece grows new worm
regeneration
