While examining the transverse section of an unidentified invertebrate, a student notices a distinct fluid-filled space between the body wall and the gut. However, the mesoderm does not form a continuous lining around this cavity; instead, it is present as scattered pouches between the ectoderm and endoderm. Based on this observation, which of the following organisms could this specimen be?

Step-by-step solution

The presence of a fluid-filled cavity between the body wall and the gut, where the mesoderm is present as scattered pouches between the ectoderm and endoderm, is characteristic of a pseudocoelom. Animals possessing a pseudocoelom are called pseudocoelomates. This feature is a hallmark of the phylum Aschelminthes. Among the given options, Ancylostoma (hookworm) belongs to the phylum Aschelminthes and is a pseudocoelomate. Fasciola (Platyhelminthes) is an acoelomate. Pheretima (Annelida) is a true coelomate. Adamsia