Placoid scales are found is

Options

A. (a) Cartilaginous fishes
B. (b) Bony fishes
C. (c) Paleontical fishes
D. (d) Lung fishes

Answer

**Step-by-Step Solution:**

1. **Understanding Placoid Scales:**
- Placoid scales are a type of scale found in certain fish species. They are characterized by their unique structure and function.

2. **Identifying the Types of Fish:**
- There are two main categories of fish: cartilaginous fish and bony fish.
- Cartilaginous fish have skeletons made of cartilage, while bony fish have skeletons made of bone.

3. **Locating Placoid Scales:**
- Placoid scales are specifically found in cartilaginous fish. This group includes species such as sharks and rays.

4. **Comparing with Other Types of Scales:**
- Bony fish have different types of scales, such as cycloid and ctenoid scales, which are not classified as placoid scales.

5. **Conclusion:**
- Based on the information, the correct answer to the question "Placoid scales are found in" is cartilaginous fish.

**Final Answer:**
- Placoid scales are found in **cartilaginous fish**.

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