. Animal biology. Zoology; Biology. STARFISH 197 227. Nervous System and Behavior.—The nervous system is less highly developed than in the phyla previously studied, there being no central ganglion. The system consists of a nerve ring encircling the perioral membrane, radial nerve cords lying at the bottoms of the ambula- cral grooves and reaching to the tips of the rays, nerves on the dorsal surface of each ray which converge toward the center of the aboral disc, and scattered nerve cells and sense cells lying among the cells of the epidermis and distributed above the nerve cords. The principa
. Animal biology. Zoology; Biology. STARFISH 197 227. Nervous System and Behavior.—The nervous system is less highly developed than in the phyla previously studied, there being no central ganglion. The system consists of a nerve ring encircling the perioral membrane, radial nerve cords lying at the bottoms of the ambula- cral grooves and reaching to the tips of the rays, nerves on the dorsal surface of each ray which converge toward the center of the aboral disc, and scattered nerve cells and sense cells lying among the cells of the epidermis and distributed above the nerve cords. The principal sense organs are the pigment spots, one at the tip of each ray, below a so-called tentacle (Fig. 105). The pigment spots are light-perceiving and the Anfer/'or Preorc*/ c/7/'cr-^ec/ AYoafh Posto/'t^/, bcrnc^. StOfTJcrcfy '"Anus. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Wolcott, Robert Henry, 1868-1934. New York ; London : McGraw-Hill Book Company, Inc.
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