phylum platyhelminthes

platyhelminthes

flat worms

ectoderm on outside

endoderm lining the gut

mesoderm in between (used for movement)

what are the three tissue layers in all platyhelminthes

gastrovascular cavity

what kind of gut do platyhelminthes have

mouth

what serves as both an entrance and exit from the gut

bilaterally symetrical

what kind of symmetry does the body have

rostral

head end, contains coordination center that can be referred to as a brain

caudal

tail end

no specialized respiratory system

what is significant about platyhelminthes respiratory system

acoelomate

flat worms are __, the outside of the gut is directly continous with the mesoderm, there is no coelomic cavity so the gut is not free inside the body

class turbellaria

not parasitic (free living)

planaria (whole mount)

• freshwater ponds

• carnivore

• sensory flaps on sides

• pharynx can protrude from mouth

planaria cross secctions

cilia

1 of two ways planaria move, help to glide over surface

muscle

1 of two ways planaria move, allows to bend and change direction

class tremadota (flukes)

• parasitic

• life cycles of parasites are complex, there are intermediate hosts and life stages

opisthorchis/clonorchis (whole mount)

the liver fluke

both sexes in one

human parasite

where raw fish is a delicacy

how do opisthorchis infect the human body

in the feces

how do opisthorchis small brown eggs exit from a humans body

when they are eaten by some freshwater snails

how do liver fluke eggs hatch

miracidium

liver fluke or opisthorchis hatchling

after several metamorphoses

when do the opisthorchis infect freshwater fish

liver fluke enters digestive system and migrate from small intestine through the bile duct to liver to mature and produce eggs

how do liver flukes get to the liver

through bile duct to the digestive system

how do liver fluke eggs exit the body through the feces

class cestoda

• parasitic tapeworms

• extremely flat

• body divided into segments

• no digestive system (absorb through body walls)

scolex whole mount

• cestoda

• big circles are suckers

• disc of hooks at tip

• large segments are full reproductive machines

suckers and hooks

how do tapeworms hold on

mature proglottid of scolex

• branched uterus (has hundreds of eggs in each segment)

cestode life cycle

taenia in cow or pigs - larvae encyst flesh of the animal - when human eats infected meat (uncooked), live cysts break down during digestion - scolecies turn right side out - attach themselves to mucous membrane of intestine by hooks and suckers - become sexually mature

auricles

in planaria there is a head end with a pair of black, light sensitive spots that are chemoreceptors.

color of planariawould make them blend in and be invisible at bottom of ponf

mesoderm

what layer is muscular