Alimentary canal is absent in

An animal without segmentation is:

Animals of this phylum possess an incomplete digestive tract.

Cysticercus of $Taenia$ develops in

Which of the following organisms has only a single opening that serves as both the mouth and the anus?

In the life history of the liver fluke,the following stages are present: $(1)$ Cercaria,$(2)$ Metacercaria,$(3)$ Sporocyst,$(4)$ Redia,$(5)$ Miracidium. What is their proper sequence?