Shell fish include

Options

A. prawn
B. crab
C. oysters
D. fishes

Answer

### Step-by-Step Solution:

1. **Definition of Shellfish**: Shellfish are aquatic animals that have a calcareous exoskeleton. They are primarily categorized into two groups: crustaceans and mollusks.

2. **Classification**: Shellfish belong to the phylum Mollusca and the subphylum Crustacea. The most common examples include prawns, crabs, and oysters.

3. **Characteristics of Shellfish**:
- **Exoskeleton**: Shellfish have an external shell made of calcium carbonate, which provides protection.
- **Habitat**: They are typically found in marine environments.

4. **Examples of Shellfish**:
- **Prawns**: These belong to the class Malacostraca within the subphylum Crustacea.
- **Crabs**: Also part of the class Malacostraca, crabs have a hard exoskeleton but do not have shells made of calcium carbonate.
- **Oysters**: These are mollusks that have a hard, calcareous shell and are a prime example of shellfish.

5. **Conclusion**: Among the examples provided, oysters are classified as shellfish due to their calcareous shell and habitat in the mollusks family.

### Final Answer:
Shellfish include prawns, crabs, and oysters, with oysters being a notable example due to their calcareous shell.

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