Question

In which of the following animals, single opening is used for both ingestion and egestion while removal of metabolic waste products is through body wall?

Hydra and Obelia

Taenia and Fasciola

Nereis and Hirudinaria

Limulus and Locusta​

Answer 1

Taenia and Fasciola


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Answer 2

In Taenia and Fasciola , single opening is used for both ingestion and egestion while removal of metabolic waste products is through body wall.

• Taenia and Fasciola are members of the phylum Platyhelminthes which are commonly called flatworms.
• Their digestive system is incomplete having a single opening that serves both as mouth and anus. It is thus used for both ingestion and egestion.
• Nereis and Hirudinaria are members of Annelida and have a complete digestive system.
• Similarly, Limulus and Locusta​ are members of Arthropoda and have a complete digestive system.