Population density of aquatic animals in some waterbody is measured in term of per

Options

A. `m^2`
B. `m^4`
C. m
D. `m^3`

Answer

To solve the question regarding the population density of aquatic animals in a water body, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Population Density**:
- Population density refers to the number of individuals of a species per unit area or volume. In this case, we are dealing with aquatic animals in a water body.

2. **Identifying the Measurement Units**:
- For terrestrial organisms, population density is typically measured in terms of individuals per unit area (e.g., individuals per square meter). However, aquatic environments are three-dimensional, and we need to consider volume.

3. **Defining the Volume of Water**:
- A water body is a three-dimensional space, and when we measure population density in aquatic environments, we often refer to the volume of water rather than just the surface area.

4. **Using the Correct Formula**:
- The formula for population density (n) is given by:
\[ n = \frac{\text{Number of organisms}}{\text{Volume of water}} \]
- Since we are measuring in a three-dimensional space, the volume is expressed in cubic meters (m³).

5. **Considering the Four-Dimensional Aspect**:
- The video transcript mentions that water bodies can be considered four-dimensional. This is because they have depth in addition to surface area, which can complicate measurements. However, for practical purposes, we can still consider the volume in cubic meters.

6. **Finalizing the Denominator**:
- Therefore, when we refer to the population density of aquatic animals, we express it in terms of "per cubic meter" (m³). This means the denominator in our measurement is m³.

### Conclusion:
The population density of aquatic animals in a water body is measured in terms of "per cubic meter" (m³).

---