In certain animals, the body cavity is not lined by mesoderm. Instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Which of the following organisms exhibits this specific body plan?

Step-by-step solution

The body cavity described is a pseudocoelom, where the mesoderm is present as scattered pouches between the ectoderm and endoderm. Animals possessing a pseudocoelom are called pseudocoelomates. According to NCERT, members of the phylum Aschelminthes are pseudocoelomates. Ascaris belongs to Aschelminthes and is therefore a pseudocoelomate. Fasciola belongs to Platyhelminthes, which are acoelomates (lacking a body cavity). Pheretima is an annelid and is a true coelomate. Adamsia is a cnidarian, which is diploblastic