Question

Protozoan in which cilia are confined only to juvenile stages is:

• A. Paramecium
• B. Vorticella
• C. Acineta
• D. Euglena

Hint:

Acineta is ciliated only in the larval stage—adults are sessile with suctorial tentacles.

Answer 1

The Correct Option is C

- Acineta is a suctorian protozoan belonging to class Ciliophora.
- In its larval (juvenile) stage, it is ciliated and free-swimming.
- Upon maturing, it loses its cilia and becomes sessile, using tentacle-like structures to capture food.
Other options:
- Paramecium and Vorticella retain cilia throughout their lives.
- Euglena moves using a flagellum, not cilia.

Answer 2

The protozoan in which cilia are confined only to the juvenile stages is Acineta.

Acineta is a genus of ciliates that exhibit a unique developmental pattern. During their juvenile or early stages of life, these organisms possess cilia, which are hair-like structures used for locomotion and feeding. However, as they mature, Acineta lose their cilia and become sessile, meaning they remain fixed in one place.

This transition from a motile juvenile stage with cilia to a stationary adult form is significant in their life cycle and adaptation. The cilia in juvenile Acineta help them move through water and locate suitable environments before settling down.

Once settled, the adults rely on other specialized structures to capture food rather than locomotion by cilia. This characteristic distinguishes Acineta from many other ciliates that retain cilia throughout their life.

Hence, Acineta is notable for having cilia only in its juvenile stages, highlighting a fascinating aspect of protozoan development and adaptation.