Cephalization

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cephalization

[‚sef·ə·lə′zā·shən]
(zoology)
Anterior specialization resulting in the concentration of sensory and neural organs in the head.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Cephalization

 

the intensified development of the cephalic portion of the body in bilaterally symmetric animals during the process of evolution. The head end of the body, which includes the oral orifice, is first to experience new objects in the environment. As a result, the sense organs (vision, olfaction, touch, and hearing, the latter being developed only in vertebrates) and the sections of the nervous system that regulate the sense organs and make up the brain are concentrated in the head end of the body. In vertebrates a skull has developed to protect the aforementioned organs. In invertebrates this protective function is performed by a hard external cover. In cephalopods the brain is protected by a cartilage capsule.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.