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| Phylum Annelida |
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 Free-living, terrestrial or aquatic form (freshwater or marine). |
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 Body is long, cylindrical and metamerically segmented. |
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 Body wall consists of cuticle, epidermis and musculature. |
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 Body cavity is a true coelom, lined by epithelium. |
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 Digestive system is complete. |
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 Respiration is either through skin or through gills. |
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 Excretion with the help of characteristic nephridia. |
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 Presence of a circulatory system (closed type). Hemoglobin dissolved directly in the plasma. |
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 Nervous system consists of a nerve ring and a double ventral nerve cord with segmental ganglia. |
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 Locomotion with the help of setae or parapodia. |
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 Reproduction by sexual methods. Either unisexual or bisexual development may be direct or indirect. |
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 Body has a true coelom. |
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| fig. 10.13 - Examples of Annelida |
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| The phylum is divided into four classes |
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| fig. 10.14 - Anterior Segments of Nereis |
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| fig. 10.15 - Earthworm Anatomy |
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