Identify the fish which is ureotelic.

Options

A. Shark
B. Catfish
C. Ray
D. Petromyzon

Answer

**Step-by-Step Solution:**

1. **Understanding Ureotelism**: Ureotelism refers to the excretion of urea as the primary nitrogenous waste product. This is different from ammonotelism, where ammonia is excreted.

2. **Identifying Common Waste Products in Fish**: Most fish excrete ammonia as their waste product because it is highly soluble in water and can be easily eliminated. This is typical for many aquatic organisms.

3. **Examining the Options**: The question provides options, and we need to identify which fish is ureotelic. Among the common fish types:
- Sharks, catfish, and rays typically excrete ammonia.
- Petromyzon (lampreys) is known to excrete urea instead of ammonia.

4. **Conclusion**: Since Petromyzon is the only fish listed that excretes urea, it is classified as ureotelic. Therefore, the correct answer is Petromyzon.

5. **Final Answer**: The fish that is ureotelic is **Petromyzon**.

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