Fertilization in Leucosolenia is

Options

A. Internal & Cross
B. External & Self
C. Internal & Self
D. External & Cross

Answer

**Step-by-Step Solution:**

1. **Understanding the Organism**: Leucosolenia is a type of sponge, which belongs to the phylum Porifera. It is important to know the basic biology of the organism to understand its reproductive process.

2. **Sperm Release**: Leucosolenia releases sperm into the seawater. This is the first step in the fertilization process, where the male gametes are expelled into the environment.

3. **Sperm Entry**: The released sperm then enter the body of the sponge. This indicates that the fertilization process involves the interaction of sperm from one sponge with the ova of another sponge.

4. **Location of Ova**: The ova (female gametes) are located in the mesenchyme, which is a gelatinous substance found in the body wall of the sponge. This is crucial for understanding where fertilization occurs.

5. **Fertilization Process**: The sperm fertilizes the ova within the mesenchyme. This process occurs inside the body of the sponge, which is key to determining the type of fertilization.

6. **Type of Fertilization**: Since the sperm comes from outside and fertilizes the ova inside the sponge, this is classified as internal fertilization. Additionally, because the sperm comes from a different sponge, this is also classified as cross fertilization.

7. **Conclusion**: Based on the above observations, the fertilization in Leucosolenia is both internal and cross fertilization. Therefore, the correct answer is option 1: internal and cross.

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