Hatschek's nephridium is present in

Options

A. Herdmania
B. Branchiostoma
C. Labeo
D. Frog

Answer

To determine where Hatschek's nephridium is present, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Term "Hatschek's Nephridium":**
- Hatschek's nephridium is a type of excretory organ found in certain chordates. It is important to know which groups of animals possess this structure.

2. **Identify the Groups of Chordates:**
- Chordates are divided into three main subphyla: Urochordata (tunicates), Cephalochordata (lancelets), and Vertebrata (vertebrates).

3. **Examine the First Option - Herdmania:**
- Herdmania is a member of the Urochordata subphylum. Urochordates do not possess Hatschek's nephridium, as they have a different excretory system. Therefore, this option is incorrect.

4. **Examine the Second Option - Branchiostoma:**
- Branchiostoma, commonly known as amphioxus or lancelet, belongs to the Cephalochordata subphylum. This group is known to have Hatschek's nephridium, which functions in excretion. Thus, this option is correct.

5. **Examine the Third Option - Libio:**
- Libio refers to a type of fish, which falls under the Vertebrata subphylum. Vertebrates do not possess Hatschek's nephridium; they have more complex excretory systems. Therefore, this option is incorrect.

6. **Examine the Fourth Option - Frog:**
- Frogs are amphibians and also belong to the Vertebrata subphylum. Like other vertebrates, frogs do not have Hatschek's nephridium. Thus, this option is incorrect.

7. **Conclusion:**
- Based on the analysis of the options, Hatschek's nephridium is present in Branchiostoma (amphioxus), making it the correct answer.

### Final Answer:
Hatschek's nephridium is present in **Branchiostoma**.

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