Which of the following does not show regeneration?

Options

A. Mucor
B. Planaria
C. Sponges
D. Starfish

Answer

To determine which of the following organisms does not show regeneration, we will analyze each option provided: mucor, planaria, sponges, and starfish.

### Step-by-Step Solution:

1. **Understanding Regeneration**:
- Regeneration is a form of asexual reproduction where an organism can regrow lost body parts. It is important to identify which organisms possess this ability.

2. **Analyzing Mucor**:
- Mucor is a type of fungus. Fungi reproduce asexually primarily through spore formation, not regeneration. Therefore, mucor does not exhibit regeneration.

3. **Analyzing Planaria**:
- Planaria are flatworms that belong to the phylum Platyhelminthes. They have a well-known ability to regenerate lost body parts, such as their tails. Thus, planaria do show regeneration.

4. **Analyzing Sponges**:
- Sponges belong to the phylum Porifera. They also have the capability to regenerate lost parts. If sponges lose a portion of their body, they can regenerate it, indicating they do show regeneration.

5. **Analyzing Starfish**:
- Starfish belong to the phylum Echinodermata. They are known for their ability to regenerate lost arms. This ability is often used as a defense mechanism, meaning starfish do exhibit regeneration.

6. **Conclusion**:
- Among the options provided, mucor is the only organism that does not show regeneration. Therefore, the correct answer is **mucor**.

### Final Answer:
The organism that does not show regeneration is **mucor**.