Which of the following is not a semelparous organism?

Options

A. Pacific salmon
B. Lamprey
C. Spider
D. Cow

Answer

To determine which of the following organisms is not semelparous, we need to understand the definitions of semelparous and iteroparous organisms.

### Step-by-Step Solution:

1. **Define Semelparous and Iteroparous Organisms**:
- Semelparous organisms are those that reproduce only once in their lifetime. This is a strategy where the organism invests all its energy in a single reproductive event.
- Iteroparous organisms, on the other hand, reproduce multiple times throughout their lives. They can have several reproductive cycles.

2. **Analyze the Given Options**:
- We need to look at the organisms listed in the options and classify them based on their reproductive strategies.

3. **Identify Semelparous Organisms**:
- **Pacific Salmon**: Known for spawning once and then dying, hence it is semelparous.
- **Lamprey**: Similar to salmon, lampreys also reproduce once and then die, making them semelparous.
- **Spider**: Many spider species reproduce once and die after laying eggs, categorizing them as semelparous.

4. **Identify the Iteroparous Organism**:
- **Cow**: Cows can reproduce multiple times throughout their lives, making them iteroparous.

5. **Conclusion**:
- Among the options provided, the cow is the only organism that is not semelparous. Therefore, the answer is the cow.

### Final Answer:
The organism that is not semelparous is the **cow**.

---