The body of the ______ is circular in cross-section, hence, the name roundworms. They may be free living, aquatic and terrestrial or parasitic in plants and animals.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. Aschelminthes.
- A very large and heterogeneous cluster of animals have traditionally been classified together in a group variously known as the Aschelminthes.
- They are called roundworms because they appear circular in cross-section. They are unsegmented.
- The body wall consists of a firm, non-living resistant cuticle, syncytial epidermis (a continuous layer of cytoplasm with scattered nuclei) and muscle layer. The muscle layer consists of longitudinal fibres only. The epidermis lacks cilia.