Question

platyhelminthes posses true muscle cells rather than epitheiall-musclar cells as seen in the cnidarians.

A)why is this? what types of muscles are seen in Planaria? How does each type function?

platyhelminthes lack a body cavity.

B)what takes up the space between the internal organs?

Answer 1

Platyhelminthes posses true muscle cells rather than epitheiall-muscle cellsas ceen in the cnidarians because they have diffrent positions so their evolution and development differs..

Planaria Circular Muscles Fibre and Longer Muscles Threads

Their function is to circular movement and longitudnal movement regularly.

B.lacks body cavity means not fully developed mesoderm .On both sides only two germ layer are present.They are acloemates don not pisses body cavity Hence no fluid filling cavity .Only internal organs are present such as digestive or respiratory system