eguruchela

The phylum :Annelida

  • Select language :

    • The word Annelida is derived from Latin word annulus which means little ring.

    They may be aquatic or terrestrial, free-living, and sometimes parasitic.

    They exhibit organ-system level of body organisation and bilateral symmetry.

    They are triploblastic, metamerically segmented and coelomate animals.

    They possess longitudinal and circular muscles that helps in locomotion.

    Aquatic annelids like Nereis possess lateral appendages, parapodia, which help in swimming.

    A closed circulatory system is present. Nephridia help in osmoregulation and excretion.

    Neural system consists of paired ganglia connected by lateral nerves to a double ventral nerve cord.

    Nereis, an aquatic form, is dioecious, but earthworms and leeches are monoecious.

    Reproduction is sexual.

    Organization Level : Organ- system

    Symmetry : Bilateral

    Coelom : Coelomate

    Respiratory system : Absent

    Digestive system : Complete

    Circulatory System : Present

    Examples : Nereis, Pheretima (Earthworm) and Hirudinaria (Blood sucking leech).

    Nereis Earth wormHirudinaria
    Nereis Nereis Hirudinaria