The body of the Nemertean is made of a layer of glandular epidermis (full of cilia), a layer of connective tissue, and a thick muscular layer. Lack exoskeleton and cuticle, but can secrete a toxic substance for protection. They are quite often colourful (showing there toxicity?) or in contrast dull and plain. The musculature is made up of a thin layer of circular muscle, surrounding a think inner layer of longitudinal muscles. Helical muscles connect the longitudinal and circular muscles and allow for twisting and coiling. Dorsoventral muscles are responsible for flattening the body.
Respiration is achieved through diffusion and circulation is made possible by a coelmic system with peripheral vessels carrying fluid throughout body. The Nemertean nervous system consists of a brain and several nerve cords. The brain is 4 anterior ganglia arranged in a circular ring. The nerve cords are filled with non-circulating neuroglobin, which extends time restraints on oxygen intake. The excretory system is made of two anterior fore-gut protonephridia which filter the fluid and send the wastes to collection ducts which lead to the anus for removal from body.
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