Type of fertilization in sponges is

Options

A. self , internal
B. cross, internal
C. cross, external
D. self ,external

Answer

### Step-by-Step Solution:

1. **Understanding Sponges**: Sponges are simple aquatic animals that belong to the phylum Porifera. They exhibit a unique reproductive strategy.

2. **Hermaphroditism in Sponges**: Sponges are generally hermaphrodites, meaning that each individual has both male and female reproductive organs. This allows them to produce both sperm and eggs.

3. **Fertilization Type**: Although sponges have both male and female reproductive organs, they do not typically self-fertilize. Instead, they engage in cross-fertilization, where sperm from one sponge fertilizes the eggs of another sponge.

4. **Internal Fertilization**: The fertilization process in sponges is internal. This means that the sperm is transferred into the body of the sponge, where it fertilizes the eggs.

5. **Development of Larvae**: After fertilization, the development of the fertilized egg leads to a larval stage. This larval stage is distinct from the adult sponge and is typically free-swimming before it settles down to form a new sponge.

6. **Conclusion**: Therefore, the type of fertilization in sponges is both cross and internal.

### Final Answer:
The type of fertilization in sponges is **cross-fertilization** and it is **internal**.

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