Nereis

         Nereis or Neanthes is a marine polychaete annelid that lives in burrows in sea bottom and comes out in nighttime to prey upon small animals. N. virens  (Sandworm), N. pelagica (Type-species) and N. succinea (Clam worm) are common species of Nereis.
          Body of Nereis is dorsoventrally flattened, segmental and 30-40 cm long having 80 to 120 segments and cleavable into acron, trunk and pygidium.  Acron is divisible into anterior prostomium and posterior peristomium and a let out in between on the ventral nerve.  Trunk is metamerically segmented and segments are called metameres or somites each one of which bears a couplet of parapodia. The last segment is called pygidium that bears an anus slightly on the dorsal font and a pair of thread like anal cirri and several(prenominal) minute sensory papillae on the dorsal side. 
PARAPODIUM
          Parapodia are opposite locomotory organs of the body attached on the lateral side of each trunk segment. Each parapodium is made of two lobes, that is to say dorsally placed notopodium and ventrally placed neuropodium. Both lobes assoil thread-like appendages called dorsal and ventral cirri.



The two lobes of parapodium are supported internally by two chitinous rods known as aciculum, on the apical part of which at that place are bundles of long, chitinous setae or chaetae which project beyond the outer margin.  Nephridiopore is situated on the parapodium snug the ventral cirrus.
SKIN
         Skin is made of tall columnar cells and disjointed glandular and sensory cells and is richly supplied with blood vessels. Outer come along of epidermis is coated with a layer of tough cuticle which carries a number of small pores for glands. Below the epidermis there are circular and longitudinal muscles in bundles and some abdominal external oblique muscle strands that help to carry out lateral undulation of body.
COELOM
         The celom is schizocoelom but true perivisceral cavity that is made of an outer parietal peritoneum and an inner visceral peritoneum that surrounds the alimentary...If you want to get a just essay, order it on our website: Ordercustompaper.com



If you want to get a full essay, wisit our page: write my paper