What is not similar in coelenterata and ctenophora?

Options

A. Body wall
B. Digestion
C. Symmetry
D. Metagenesis

Answer

To answer the question "What is not similar in Coelenterata and Ctenophora?", we will analyze the characteristics of both phyla and identify the differences.

### Step-by-Step Solution:

1. **Understanding the Phyla**:
- Coelenterata, also known as Cnidaria, includes organisms like jellyfish, corals, and sea anemones. They possess stinging cells (cnidocytes) for defense and capturing prey.
- Ctenophora, commonly referred to as comb jellies, are exclusively marine animals characterized by their unique method of locomotion using cilia.

2. **Identifying Similarities**:
- **Body Wall**: Both phyla have a similar body wall structure that consists of two layers of cells (epidermis and gastrodermis) with a gelatinous mesoglea in between.
- **Digestion**: Both Coelenterata and Ctenophora have an incomplete digestive system, meaning they have a single opening that serves as both mouth and anus.
- **Symmetry**: Both exhibit radial symmetry, which means their body parts are arranged around a central axis.

3. **Identifying Differences**:
- **Metagenesis**: This is a significant difference. Coelenterata exhibit metagenesis, which is the alternation of generations between two forms: the polyp (asexual form) and the medusa (sexual form). Ctenophora do not exhibit this form of reproduction; they do not alternate between different body forms.
- Therefore, metagenesis is a feature exclusive to Coelenterata and is not found in Ctenophora.

4. **Conclusion**:
- The aspect that is not similar between Coelenterata and Ctenophora is **metagenesis**.

### Final Answer:
The feature that is not similar in Coelenterata and Ctenophora is **metagenesis**.

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