Ammonia is the chief excretory substance in

Options

A. Camel and whale
B. Cartilginous fishes
C. Whale and Tortoise
D. Fresh water fishes

Answer

To answer the question "Ammonia is the chief excretory substance in," we need to analyze the options provided and understand the excretory products of different organisms.

### Step-by-Step Solution:

1. **Identify Excretory Products**:
- The three main types of nitrogenous waste excreted by animals are ammonia, urea, and uric acid.
- Ammonia is highly toxic and requires a large amount of water to be safely excreted.

2. **Understand the Context of Ammonia Excretion**:
- Ammonia is primarily excreted by aquatic animals because they have access to large volumes of water, which helps dilute the toxicity of ammonia.

3. **Evaluate the Options**:
- **Camel and Whale**: Camels are terrestrial and excrete urea, not ammonia. Whales are aquatic and can excrete ammonia, but this option is not entirely correct.
- **Cartilaginous Fishes**: These fishes (like sharks) primarily excrete urea, not ammonia.
- **Whale and Tortoise**: Whales can excrete ammonia, but tortoises are terrestrial and excrete uric acid.
- **Freshwater Fishes**: Freshwater fishes typically excrete ammonia due to their aquatic environment.

4. **Select the Correct Answer**:
- Among the options, freshwater fishes are the most accurate choice for organisms that predominantly excrete ammonia. Therefore, the correct answer is **freshwater fishes**.

### Final Answer:
Ammonia is the chief excretory substance in **freshwater fishes**.

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