The animals which do not have a steady body temperature are

Options

A. poikilotherms
B. eutherians
C. stenothermals
D. homeotherms

Answer

### Step-by-Step Solution:

1. **Understanding Body Temperature Regulation**:
- Animals can be classified based on their ability to maintain a constant body temperature. This ability is known as homeostasis.

2. **Defining Regulators and Confirmers**:
- **Regulators**: These are organisms that can maintain a stable internal body temperature regardless of external environmental conditions. For example, humans maintain a body temperature of around 37°C even if the external temperature varies significantly.
- **Confirmers**: These are organisms that cannot maintain a constant body temperature and their internal temperature fluctuates with the external environment.

3. **Identifying Cold-Blooded Animals**:
- Animals that are unable to maintain a steady body temperature and instead adjust their body temperature according to the surrounding environment are referred to as cold-blooded animals or **poikilotherms**. This group includes most reptiles, amphibians, and fish.

4. **Differentiating Warm-Blooded Animals**:
- In contrast, warm-blooded animals, also known as **homeotherms**, can regulate their body temperature internally and maintain it within a narrow range despite external temperature changes.

5. **Analyzing Other Terms**:
- **Stenothermals**: These organisms can only survive within a narrow range of temperatures and are not the answer to the question.
- **Eutherians**: This term refers to a group of mammals that give live birth and is not related to temperature regulation.
- **Urethermals**: These organisms can tolerate a wider range of temperatures but do not specifically refer to the inability to maintain a steady body temperature.

6. **Conclusion**:
- The correct answer to the question is **poikilotherms**, as these are the animals that do not have a steady body temperature.