Which is not correct for sponges?

Options

A. Internal fertilisation
B. External fertilisation
C. Gemmule formation
D. Gametes are formed from epidermal cells

Explanation

To determine which statement is not correct for sponges, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Sponges**:
- Sponges belong to the phylum Porifera.
- They exhibit a cellular grade of organization, meaning they do not have true tissues or organs.

2. **Analyzing the Options**:
- **Option A: Internal Fertilization**:
- Sponges are generally hermaphrodites, meaning they possess both male and female reproductive organs. They usually undergo internal fertilization, where sperm is transferred to the body of another sponge.
- **Option B: External Fertilization**:
- This involves the release of sperm and eggs into the environment for fertilization, which is common in organisms like frogs and fishes. Sponges do not typically engage in external fertilization; hence, this option is incorrect.
- **Option C: Gemmule Formation**:
- Gemmules are a form of asexual reproduction in sponges, allowing them to survive unfavorable conditions. This is a characteristic feature of sponges.
- **Option D: Gametes are formed from epidermal cells**:
- In sponges, gametes (sperm and eggs) are indeed formed from specialized cells in the epidermis, which is correct.

3. **Conclusion**:
- The option that is not correct for sponges is **Option B: External Fertilization**.

### Final Answer:
The statement that is not correct for sponges is **External Fertilization**.

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