There are two in every segment. The common earthworm has both a PNS and a CNS. At each segment, segmental ganglion branch off from the ventral nerve cord, thus connecting every segment to the earthworm's brain. The earthworm has a simple yet sensitive nervous system. The worm’s excretory organs are tiny nephridia. The nervous system of the earthworm is split up into segments just like the rest of its body. These are located in the dorsal side of the alimentary canal in the third segment, in a groove between the buccal cavity and pharynx. Sensory fibers (afferent fibers) carry impulse to central nervous system. The central nervous system consists of a pair of cerebral ganglia or supra-pharyngeal ganglia which fuse to form brain which is whitish pear-shaped structure. Motor fibers (efferent fibers) carry impulse back to effective organs or different parts of body from central nervous system. The brain is formed of the supra pharyngeal ganglia. Nervous system is well developed in the earthworm.It consists of central, peripheral and autonomic nervous system. Introduction to Circulatory System in Earthworm: Earthworms possess a closed circulatory system in which blood always flows in the vessels and never comes in direct contact with tissues. He ob- After Thirteenth Segment in Earthworm. 10. The peripheral nerves are mixed because they are afferent and efferent. Series B - Biological Sciences, 10.1098/rspb.1943.0008, 131, 864, (271-295), (1943). Its cerebral ganglion, or brain, is connected to the ventral nerve cord, which runs the length of its body. Use the preceding diagram to locate some nephridia. Cuvier (26) was one of the first to identify the divisions of the nerv-ous system of the earthworm. The nerve ring is composed of: (1) A pair of suprapharyngeal ganglia or brain lying on the dorsal surface of the pharynx in the third segment; The brain is above the pharynx and is connected to the first ventral ganglion. Earthworm : Nervous System. The nervous system of earthworms. Nervous System of Earthworm: The central nervous system consists of a nerve ring encircling the pharynx and a ventral nerve cord with ganglionic swellings. The ganglia above the pharynx serve as the brain of the earthworm. nervous system of earthworm A group of organs which controls and coordinates the various activities and movements of body parts is known as ner­vous system. color the digestive system green, the nervous system blue, the reproductive system yellow. A swelling or ganglion in It is a bilobed mass of nervous tissue situated on the dorsal wall of the pharynx in 3rd seg-ment. The CNS consists of a bilobed brain (cerebral ganglia, or supra-pharyngeal ganglion), sub-pharyngeal ganglia, circum-pharyngeal connectives and a ventral nerve cord.. Earthworms' brains consist of a pair of pear-shaped cerebral ganglia. Central nervous system. Earthworm - Nervous System: Above: the anterior part of the central nervous of the earthworm Lumbricus terrestris. There are large amounts of chemoreceptors in the worm. These ganglia are connected to one common nerve cord which runs down the length of its back. The brain is important for movement, if the brain of the earthworm is removed, the earthworm will move continuously. The visceral nervous system of the earthworm: I. Nerves controlling the tone of the alimentary canal, Proceedings of the Royal Society of London. NERVOUS SYSTEM OF EARTHWORM 183 GROSS MORPHOLOGY OF THE NERVOUS SYSTEM OF THE EARTHWORM In i672 Willis (135) recognized a white lobe above the oesophagus of the earth-worm as the brain, "cerebrum mole perexiguum." In earthworm, impulse is also travel from one ganglion to another ganglion through ventral nerve cord. The ganglia found below the pharynx in the 4th segments is called the subpharyngeal ganglia. 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