10 main characteristics of Phylum Annelida are given below:
- Bilaterally symmetrical and vermiform.
- Body has more than two cell layers, tissues and organs.
- Body cavity is a true coelom, often divided by internal septa.
- Body possesses a through gut with mouth and anus.
- Body possesses 3 separate sections, a prosomium, a trunk and a pygidium.
- Has a nervous system with an anterior nerve ring, ganglia and a ventral nerve chord.
- Has a true closed circulatory system.
- Has no true respiratory organs.
- Reproduction normally sexual and gonochoristic or hermaphoditic.
- Troch phore lava is present during indirect development.