What are the salient features exhibited by polychaetes ?

* These are marine forms.
* Commonly called bristle worms.
* Some are free moving and other burrowing.
* Clitellum is absent, gonoducts absent.
* Head is distinct with sense organs.
* Parapodia has many setae that help in locomotion and respiration.
* Unisexual, Fertilisation external.
* Development indirect.
Eg : Nereis (Sand worm)
Arenicola (Lugworm)