Question

Which of the following statements is true about the worm phyla?a) Annelida and Nematoda phyla are the simplest of all worms while Platyhelminthes are complex wormsb) many annelids are parasites, but flatworms and roundworms help fertilize the soilc) Annelida, Platyhelminthes, and Nematoda all have animals with a coelomd) most annelids are free-living animals, but most flatworms and roundworms are parasites

Answer 1

Annelids show parasitic and commensal symbioses, which means that they are not free-living animals. Therefore, d) is incorrect.

The worms are categorized by being acoelomate (does not have a coelom), pseudocoelomate (having a coelom divided in half) and coelomate (having a full coelom). Therefore, c) is also incorrect.

Many annelids are parasites, but only earthworms help fertilize the soil (not flatworms or roundworms). Therefore, b) is wrong as well.

Annelida and Nematoda are simpler than Platyhelminthes because of their structural and internal organization. Therefore,