platyhelminthes (flatworms) Flashcards
what type of body plan
sac
do they have a coelom (body cavity)?
no: acoelomates
what kind of symmetry
bilateral
which systems do they lack
respiratory, circulatory
what is used to circulate substances from cell to cell (eg. oxygen)
diffusion
free living flatworms have muscles for which system
reproductive, excretory, digestive
what are the germ layers that give them greater complexity
meso, ecto, endo derm
describe freshwater planarians and where do they live to get food
small, flat worms that live in lakes, ponds, streams, and springs where they feed on living/dead organisms (eg. worms, crustaceans)
describe the planarians excretory system
Network of interconnecting canals
Beating of cilia in the flame cells keeps waste moving to exeretory pores
describe the planarians nervous system
Ladder like
Small anterior brain and 2 lateral nerve cords joined by cross-branches / transverse nerves.
what sense organs do planarians have
light-sensitive eyespots, chemosensitive organs on auricles
do they experience cephalization (sensory & neural structures in the head region)
yes
describe planarians digestive sustem
Incomplete digestive system: Only 1 opening / 2 way system
Pharynx leads into three branched gastrovascular cavity
what kind of digestion do planarians have
extracellular and intracellular
what three muscle layers do planarians have & what kind of movement do they allow
Outer circular, inner longitudal, diagonal layer
• Allows For varied movement
