In fishes, the cranial nerves are

Options

A. 6 pairs
B. 8 pairs
C. 10 pairs
D. 12 pairs

Answer

**Step-by-Step Solution:**

1. **Understanding Cranial Nerves**: Cranial nerves are the nerves that emerge directly from the brain and are responsible for various functions, including sensory and motor functions.

2. **Cranial Nerves in Humans vs. Fishes**: In humans and most mammals, there are 12 pairs of cranial nerves. This includes a variety of nerves that serve different functions throughout the body.

3. **Cranial Nerves in Fishes**: In fishes, the number of cranial nerves is different. Fishes have only 10 pairs of cranial nerves.

4. **Identifying the Absent Nerves**: The 11th and 12th pairs of cranial nerves, which are present in mammals, are absent in fishes. This is a key difference that accounts for the lower number of cranial nerves in fishes.

5. **Listing the Cranial Nerves in Fishes**: The 10 pairs of cranial nerves in fishes include:
- Terminal nerve
- Olfactory nerve
- Optic nerve
- Epiphysis
- Midbrain nerves (including two motor nerves: oculomotor and trochlear)
- Other nerves originating from the hindbrain.

6. **Conclusion**: Therefore, the total number of cranial nerves in fishes is 10 pairs.

**Final Answer**: In fishes, there are 10 pairs of cranial nerves.

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