Nereis

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NEREIS



CLASSIFICATION:
Phylum: Annelida
class : Polychaeta
Genus: Nereis

COMMENTS:
•Nereis is commonly called rag worm or clam worm.
•The body is long, slender & dorso-ventrally flattered reaching a length of 5-30 cm.
•The body consists of distinct head followed by a no. similar segments.
•Head consists of two parts: a roughly triangular anterior lobe, the prostomium and a posterior ring like portion, the peristomium.
•Prostomium bears a pair of terminal tentacles, dorsally two pairs of eyes & ventrally a pair of jointed palps.
•Peristomium bears four slender cylindrical
tentacles on each side & a transverse aperture, the mouth on the ventral surface.
•Each segment of the body behind peristomium bears a pair of appendages known as anal cirri and terminal anus.
•At the bases of parapodia on the ventral side in each segment are the paired openings of the nephridia, the nephridiopores.
•Sexes are separate, gonads develop temporarily during reproductive season.The sexual phase of Nereis is called Heteronereis.




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