Question

Which one assists in locomotion?

• A. Trichocysts in Paramecium
• B. Pedicellariae of star fish
• C. Clitellum in Pheretima
• D. Posterior sucker in Hirudinaria.

Answer 1

The Correct Option is D

To determine which structure assists in locomotion, let's analyze each option:

1. Trichocysts in Paramecium: Trichocysts are small, bottle-shaped organelles found in Paramecium. They are used as a defense mechanism, releasing a thread-like structure to deter predators or anchor the organism. However, they are not involved in locomotion.
2. Pedicellariae of starfish: Pedicellariae are small pincer-like structures used by starfish primarily for cleaning the body surface and protecting against predators. They do not play a role in locomotion.
3. Clitellum in Pheretima: The clitellum is a thickened, glandular section of the body wall in earthworms (like Pheretima) that secretes mucus for copulation and cocoon formation. It is not associated with locomotion.
4. Posterior sucker in Hirudinaria: Hirudinaria, commonly known as leeches, use suckers for attachment and locomotion. The posterior sucker is especially crucial as it allows the leech to anchor firmly while moving the anterior part of its body, thereby assisting in locomotion.

Based on the analysis, the posterior sucker in Hirudinaria is the correct answer as it directly aids in locomotion by helping the organism attach and move effectively.