Which one of these animals is not a homoetherm ?

Options

A. Macropus
B. Chelone
C. Camelus
D. Psittacula

Answer

To determine which of the given animals is not a homeotherm, we need to understand what a homeotherm is. Homeotherms are animals that can maintain a stable internal body temperature regardless of external environmental conditions.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) Macropus
- B) Chelon
- C) Chameleon
- D) Citracula

2. **Define Homeotherm**: Homeotherms are organisms that can regulate their body temperature internally. This includes mammals and birds, which have mechanisms to maintain a constant body temperature.

3. **Analyze Each Option**:
- **Option A: Macropus**: This is a genus that includes kangaroos, which are mammals. Mammals are homeotherms as they can regulate their body temperature.
- **Option B: Chelon**: This refers to turtles. Turtles are reptiles and are not homeotherms; they are ectothermic, meaning their body temperature is influenced by the external environment.
- **Option C: Chameleon**: Chameleons are also reptiles and are ectothermic, similar to turtles. They cannot maintain a constant body temperature independently of their environment.
- **Option D: Citracula**: This refers to parrots, which are birds. Birds are homeotherms as they can regulate their internal body temperature.

4. **Conclusion**: Among the options, Chelon (option B) is the only one that does not maintain a constant body temperature and is therefore not a homeotherm.

### Final Answer:
The animal that is not a homeotherm is **Option B: Chelon**.