Question

give reason why animals of phylum platyhelminthes called flatworm

Answer 1

platyhelminthes are a group of invertebrates that are also called flatworms because their bodies are dorsoventrally flattened therefore they appear  like leaf like or ribbon like creatures.

Answer 2

The body is bilaterally symmetrical . However there is no true internal body cavity or coelom in which well developed organs can be accommodated . The body is flattened dorsiventrally meaning from top to bottom , which is why these animals are called flat worms