Cell Cycle and Cell Division - Meiosis
Phylum Annelida (Segmented / Ringed Worms): General Characters
- Grades of Organization: Organ system.
- Symmetry: Bilateral symmetry.
- Germ Layers: Triploblastic.
- Coelom: Coelomate.
- Habit and Habitat: Terrestrial, fresh water or marine. Free living or parasitic.
- Digestive System: Complete.
- Respiratory System: Cutaneous respiration. Some have branchial (gill) respiration.
- Circulatory System: Closed type.
- Reproduction:
- Sexual.
- Earthworms & leeches are monoecious.
- Neries is dioecious.
- Development is direct or indirect.
- Unique Features:
- Segmentation like rings.
- Longitudinal and circular muscles help in locomotion.
- Locomotory organs are setae (in earthworm) or parapodia (in Neries).
- Excretion by Nephridia.
- Paired ganglia connected by lateral nerves to a double ventral nerve cord.
- Examples:
- Pheretima (earthworm)
- Hirudinaria (blood sucking Leech)
- Neries (aquatic. Parapodia for swimming).
