3 Main Classes of Phylum Annelida | Zoology
The following points highlight the three main classes of the phylum annelida. The classes are: 1. Chaetopoda 2. Hirudinea 3. Archiannelida. Class # 1. Chaetopoda: 1. Setae develop in skin-sacs and elevated on the Para podia. 2. Segments are usually numerous, well-marked and similar throughout. 3. A large coelom, divided into chambers by septa and not continuous with blood vascular [...]