Which is a Mollusca?

Options

A. Sea Mouse
B. Sea Hare (Aplysia)
C. Sea cow
D. Sea Horse

Answer

To determine which organism belongs to the phylum Mollusca, let's analyze the options provided:

1. **Sea Mouse**: This organism is not a mollusk; it is actually a type of polychaete worm, which belongs to the phylum Annelida.

2. **Sea Horse**: The sea horse is a marine fish belonging to the family Syngnathidae and is not part of the Mollusca phylum.

3. **Sea Cow**: The sea cow, or manatee, is a marine mammal that belongs to the order Sirenia, which is also not a mollusk.

4. **Sea Hare**: The sea hare is a type of marine gastropod mollusk, which falls under the phylum Mollusca.

Based on this analysis, the correct answer is **Sea Hare**, as it is the only organism listed that belongs to the Mollusca phylum.

### Step-by-Step Solution:
1. **Identify the Options**: List the organisms given in the question.
2. **Research Each Organism**: Determine the classification of each organism.
- Sea Mouse: Annelida (not a mollusk)
- Sea Horse: Fish (not a mollusk)
- Sea Cow: Mammal (not a mollusk)
- Sea Hare: Mollusca (is a mollusk)
3. **Determine the Correct Answer**: Identify which organism is classified under Mollusca.
4. **Conclusion**: The Sea Hare is the correct answer as it belongs to the Mollusca phylum.