One example of animals having a single opening to the outside that serves both as mouth as well as anus is
One example of animals having a single opening to the outside that serves both as mouth as well as anus is
Octopus
Asterias
Ascidia
Fasciola
Solution
Fasciola hepatica (sheep liver fluke) belongs to phylum-Platyhelminthes. These worms have incomplete alimentary canal, there is a single opening for both ingestion and egestion. This is also called as blind sac body plan.