Date & Time : 20, November 2017 06:02
General Characteristics of Annelida
Annelids are mostly aquatic, marine or freshwater, but many are burrowing or free living.
Triploblastic, bilaterally symmetrical metamerically segmented body.
First Phylum to possess a true coelom.
Elongated and vermiform.
Cuticle (secreted by epidermis) covers the whole body.
Locomotory organ - segmentally arranged setae or chaetae.
Appendages (if present) are unjointed. For example, parapodia in polychaetes.
Respiration through body surface, in some by gills.
Blood vascular system - closed type. Blood is red due to the presence of haemoglobin.
Excretion by nephridia (paired and segmented).
Nervous system consist of brain and segmental ganglia.
Direct development (when sexes are separate), indirect (when sexes are united).
Classification of Annelida
Phylum Annelida is classified into three classes:
A Few Examples