The excretory organs of Palaeomon are

Options

A. Malpighian tubules
B. Nephridia
C. Green glands
D. Kidney

Answer

### Step-by-Step Solution:

1. **Identify the Organism**: The question asks about the excretory organs of Palaeomon, which is a genus of freshwater shrimp.

2. **Understand Excretion in Palaeomon**: In Palaeomon, excretion primarily occurs through specialized structures known as green glands.

3. **Name the Excretory Organs**: The green glands are also referred to as antennal glands or "medium sex" glands. They play a crucial role in both excretion and osmoregulation.

4. **Describe the Function of Green Glands**:
- The green glands receive blood through antennary arteries.
- They perform ultrafiltration, where water and dissolved substances are filtered out from the blood.

5. **Filtration Process**:
- The filtered material (filtrate) moves into a structure called the labyrinth.
- Useful substances are reabsorbed back into the bloodstream through a process known as selective absorption.

6. **Formation of Urine**:
- The waste products that remain after filtration are collected and passed into the bladder.
- The excretory fluid is then transported from the renal sac through the ureter to the renal apertures.

7. **Conclusion**: Therefore, the excretory organs of Palaeomon are the green glands.