Which of the following is not a character of the echinoderm life cycle ?

Options

A. Radial symmetry
B. Bilateral symmetry
C. Asymmetrical
D. Both (A) and (C)

Answer

To determine which of the following is not a character of the echinoderm life cycle, we need to analyze the options given:

1. **Radial symmetry**: Echinoderms, such as starfish, exhibit radial symmetry in their adult form. This means their body can be divided into similar halves by multiple planes. This is a characteristic of echinoderms.

2. **Bilateral symmetry**: Echinoderms also exhibit bilateral symmetry in their larval stage. This means their body can be divided into two equal halves by only one plane. This is also a characteristic of echinoderms.

3. **Asymmetrical**: Asymmetry means that the organism cannot be divided into equal halves by any plane. Echinoderms do not exhibit asymmetry; they possess either radial or bilateral symmetry at different life stages.

4. **Both a and c**: This option suggests that both radial symmetry (a) and asymmetry (c) are characteristics of echinoderms. However, since asymmetry is not a characteristic of echinoderms, this option is also incorrect.

Based on the analysis:

- The correct answer is **Asymmetrical** (Option 3), as it is not a character of the echinoderm life cycle.

### Step-by-Step Solution:
1. **Identify the characteristics of echinoderms**: Understand that echinoderms, like starfish, exhibit radial symmetry in adults and bilateral symmetry in larvae.
2. **Evaluate each option**:
- Radial symmetry: Present in adults.
- Bilateral symmetry: Present in larvae.
- Asymmetrical: Not present in echinoderms.
- Both a and c: Incorrect because asymmetry is not a characteristic.
3. **Conclude**: The characteristic that is not part of the echinoderm life cycle is asymmetrical.