How does class polychaeta differ from other classes of phylum Annelida?

Explanation

### Step-by-Step Solution

1. **Introduction to Phylum Annelida**:
- Phylum Annelida consists of segmented worms and is divided into three main classes: Polychaeta, Oligochaeta, and Hirudinea.

2. **Characteristics of Class Polychaeta**:
- **Unisexuality**: Polychaetes are unisexual, meaning that male and female individuals are separate. This is different from some other classes where hermaphroditism may occur.
- **Parapodia**: They possess parapodia, which are paired, lateral appendages that assist in locomotion. Parapodia often have bristles (setae) and are not present in the other classes.
...