PLATHEHELMINTHES PPT BY VISHNU ME

3. PLATYHELMINTHES
 In Greek the word platys – flat ; helmins –
worm thus , platy helminthes mean
flatworm.
 The body is flattened dorsiventrally (top to
bottom).
 It is bilaterally symmetrical (i.e. the left and
right halves body have the same design).
 Its body has thin, soft, leaf like structure.
 They are acoelomate animal (they don’t have
body cavity).
 Circulatory and respiratory systems and
skeleton are absent

4.  Some flatworm species are free-living (or)
and live in fresh water, shallow water.
However, nearly half of flatworm species are
parasitic.
 The 3 layers are
ectoderm (outer) ,
mesoderm (middle),
endoderm (inner).
 They are triploblastic animals (3 layers from
which differentiated tissues can be made).
 They are aquatic terrestrial .
 Most animals are mobile.

5.  They are :
Eukaryotic
Multicellular
Heterotrophic
 Hermaphrodite both male and female
reproductive organs occur in same individual
 Planaria comes under turbellaria class which
are free living , aquatic , both marine and fresh
water and few are terrestrial .
 Trematodes and Cestodes are another class
which are parasitic
 Some examples of platyheminthes are :
a) planaria
b) liver fluke
c) tape worm