All the following are examples of commensalism except :

Options

A. Orchid on mango branch
B. Cattle egret and grazing cattle
C. Sea anemone and clown fish
D. Cuckoo (koel ) and crow

Answer

To solve the question "All the following are examples of commensalism except:", we need to analyze each option provided and determine whether it represents commensalism or not.

### Step-by-Step Solution:

1. **Understanding Commensalism**:
- Commensalism is a type of symbiotic relationship where one organism benefits while the other is neither helped nor harmed.

2. **Analyzing Option 1: Orchid on Mango Tree**:
- Orchids grow on mango trees to gain support. The mango tree is not affected by the presence of the orchid.
- **Conclusion**: This is an example of commensalism.

3. **Analyzing Option 2: Cattle Egret and Grazing Cattle**:
- Cattle egrets follow grazing cattle, feeding on insects that are disturbed by the cattle's movement. The cattle are unaffected by the presence of the egrets.
- **Conclusion**: This is also an example of commensalism.

4. **Analyzing Option 3: Clownfish and Sea Anemone**:
- Clownfish live among the tentacles of sea anemones, gaining protection from predators. The sea anemone is not harmed or benefited by the clownfish.
- **Conclusion**: This is another example of commensalism.

5. **Analyzing Option 4: Cuckoo and Crow**:
- The cuckoo lays its eggs in the nest of a crow, which raises the cuckoo's young. Here, the cuckoo benefits at the expense of the crow, which is harmed as it has to care for the cuckoo's offspring.
- **Conclusion**: This is not an example of commensalism; it is an example of brood parasitism.

### Final Answer:
The correct answer is **Option 4: Cuckoo and Crow**, as it is not an example of commensalism.

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