Organisms living in arctic and antarctic climatic zones are called

Options

A. Megatherms
B. Mesotherms
C. Microtherms
D. Hekistotherms

Answer

To answer the question regarding the organisms living in Arctic and Antarctic climatic zones, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Climatic Zones**:
- Arctic and Antarctic zones are known for their extremely cold temperatures, often below 0 degrees Celsius.

2. **Identify the Types of Organisms**:
- There are different categories of organisms based on their temperature tolerance: megatherms, mesotherms, microtherms, and hecistotherms.

3. **Define Each Category**:
- **Megatherms**: These organisms thrive in high-temperature environments, typically between 30 to 40 degrees Celsius. They are not suited for cold climates.
- **Mesotherms**: These organisms can survive in moderate temperature ranges. They are adaptable to alternating conditions but do not specifically thrive in extreme cold.
- **Microtherms**: These organisms can tolerate low temperatures, generally around 10 to 20 degrees Celsius. While they can survive in cooler climates, they are not specifically adapted to the freezing conditions of the poles.
- **Hecistotherms**: These organisms are adapted to very low temperatures, often below 0 degrees Celsius, and can survive in conditions that are extremely cold.

4. **Determine the Correct Category for Arctic and Antarctic Organisms**:
- Given that the temperatures in the Arctic and Antarctic regions are predominantly below 0 degrees Celsius, the organisms that inhabit these areas must be able to survive in such extreme cold.

5. **Conclusion**:
- The organisms living in Arctic and Antarctic climatic zones are best classified as **hecistotherms**, as they are specifically adapted to survive in very low temperatures.

### Final Answer:
Organisms living in Arctic and Antarctic climatic zones are called **hecistotherms**.

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