GAMNI MADAAN, Academic Content writer at EDUMARZ
Characteristic Features :
The body surface of the Members of this Phylum have segments or metameres on it .
Aquatic species of this Phylum like Nereis have lateral appendages known as parapodia which eventually help in swimming .
Nephridia which is an excretory organ in annelida helps in osmoregulation apart from performing a vital role in excretion.
General features :
Habitat : Members of this Phylum can be aquatic, free -living , parasite or terrestrial .
Symmetry : They have bilateral Symmetry.
External Morphology: They have flat or round shaped bodies.
Body Wall :They are Triploblastic ( 3 layers of body wall ).
Coelom : They are true coelomates(body cavity is present).
Level of body organisation: They have organ level of organisation .
Locomotory organ: They have parodia to help in swimming .
Due to longitudinal and circular muscles , it vastly helps in locomotion.
Alimentary canal and Digestion: They possess a complete alimentary canal that extends from mouth to anus and contains several enzymes to help in Digestion of various food substances .
Respiration and circulation : They respire through general body surface called as cutaneous respiration . Circulatory system is closed and the neural system constitutes paired ganglia which is connected by lateral nerves to a double ventral nerve cord.
Reproduction: They produce offsprings through sexual reproduction. Some animals in this Phylum are dioecious like Nereis while some are monoecious like Earthworm and leeches.
EXAMPLES :-
Pheretima (Earthworm) Hirudinaria (Blood sucking leech) and Nereis.