• The body wall of nereis is very thick.

• It consist of four parts namely from outside, the cuticle, epidermis, muscle layer and parietal peritoneum or outer coelmic epithelium.

• Cuticle is a thin, transparent and elastic chitinous envelop over the entire body surface.

• Epidermis is single layered. It consists of sensory cells, mucus secreting gland cells and supporting columnar cells.

• Muscular layer – outer circular and inner longitudinal muscles.

• The contraction of the circular muscles lengthens the body.

• The contraction of the longitudinal muscles causes side to side bending of the body.

• All muscles of nereis are non – striated.