The flatworms

*Phylum Platyhelmithes

Ken Knezick

*Flatworms have an incomplete gut!*Pharynx: Single opening in their digestive

system*Flatworms also have a excretory system *Flame cells: a network of bulb-like cells

with flagella that push water and a ‘urine-like’ substance out of the skin*Beginning of cephalization: having a head*Two eye spots enable it to distinguish between

light and dark

*Gas Exchange: diffusion*Circulation: diffusion*Excretion: flame cells*Digestion/feeding: incomplete digestive system

with one opening; the pharynx*Reproduction: hermaphroditic (possess but male

and female structures. Capable of regeneration if cut in half*Response to environment: eye spots allow for

distinguishing between light and dark*Movement: motile, may attach to host if

parasitic

*Many flatworms are parasitic: *Trematods attach themselves within the

bodies of their hosts by means of suckers, hooks, or anchors*Most have a life cycle with two hosts:*The first is always a snail*The second (adult) is almost always a

vertebrate

*The beef tapeworm:*About 1% of cattle in the U.S. are infected *20% of beef consumed is not inspected*Humans can be infected by consuming beef

‘rare’

*http://animal.discovery.com/videos/monsters-inside-me/