Blue green algea cultivated in water tanks as protein rich animal food are

Options

A. Spirillum
B. Spirulina
C. Oscillatoria
D. Nostoc.

Answer

To solve the question about which blue-green algae are cultivated in water tanks as protein-rich animal food, we can follow these steps:

### Step 1: Understand the Options
The question provides four options: spirulum, spirulina, oscillatoria, and nostoc. We need to identify which of these is known for being cultivated as a protein-rich food source.

### Step 2: Analyze Each Option
- **Spirulina**: This is a well-known blue-green algae (cyanobacteria) that is rich in protein. It contains all essential amino acids and is often used as a dietary supplement for both humans and animals.

- **Oscillatoria**: This is a filamentous cyanobacteria that does not have significant nutritional value compared to spirulina and is not primarily cultivated for food.

- **Nostoc**: This genus of cyanobacteria can form colonies but is not specifically known for being cultivated as a protein-rich food source.

- **Spirulum**: This refers to a genus of spiral-shaped bacteria that are not related to blue-green algae and are known to cause diseases, making them unsuitable for cultivation as food.

### Step 3: Identify the Correct Answer
Based on the analysis, **spirulina** is the only option that is specifically cultivated in water tanks as a protein-rich animal food.

### Final Answer
The blue-green algae cultivated in water tanks as protein-rich animal food are **spirulina**.

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