Which one of the following is poikilothermal ?

Options

A. Whale
B. Echidna
C. Tortoise
D. Fowl

Answer

To determine which of the following options is poikilothermal, we need to understand the definitions of poikilothermal and homeothermal organisms.

### Step-by-Step Solution:

1. **Define Poikilothermal and Homeothermal:**
- Poikilothermal organisms are those that cannot regulate their body temperature. Their body temperature varies with the environment. Examples include most reptiles.
- Homeothermal organisms can maintain a constant body temperature regardless of external conditions. Examples include mammals and birds.

2. **Analyze the Options:**
- **Whale:** Whales are mammals and are homeothermal. Therefore, this option is incorrect.
- **Acadena (Spiny Anteater):** This is an egg-laying mammal, which also falls under the category of homeothermal. Thus, this option is incorrect.
- **Tortoise:** Tortoises are reptiles and are poikilothermal. This makes this option correct.
- **Fowl (Bird):** Fowls are birds and are homeothermal. Hence, this option is incorrect.

3. **Conclusion:**
- The only poikilothermal organism among the options given is the tortoise.

### Final Answer:
The correct answer is **C. Tortoise**.

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