Which of he following is a poikilotherm ?

Options

A. Neophron
B. Aptenodytes
C. Vipera
D. Macaca

Answer

To determine which of the following organisms is a poikilotherm, we need to understand what poikilotherms are. Poikilotherms, also known as cold-blooded organisms, are unable to regulate their body temperature internally. Instead, their body temperature fluctuates with the temperature of their environment. Common examples of poikilotherms include fish, amphibians, and reptiles.

Now, let's analyze the options provided:

1. **Neophron**: This refers to the Egyptian vulture, which is a bird. Birds are generally warm-blooded (endothermic) and can regulate their body temperature, so Neophron is not a poikilotherm.

2. **Tenodites**: This refers to penguins, which are also birds. Like other birds, penguins are warm-blooded and can maintain a stable internal body temperature, making Tenodites not a poikilotherm.

3. **Makaka**: This refers to macaques, which are primates. Similar to humans, macaques are warm-blooded and can regulate their body temperature, so Makaka is not a poikilotherm.

4. **Vipera**: This refers to vipers, which are snakes. Snakes are reptiles and are classified as poikilotherms because they cannot regulate their body temperature and their temperature changes with the environment.

Based on this analysis, the only organism that qualifies as a poikilotherm is **Vipera**.

### Solution Summary:
The correct answer is **Vipera**, as it is a snake and a poikilotherm, while the other options (Neophron, Tenodites, and Makaka) are warm-blooded organisms.