Cephalization refers to an evolutionary trend by which the neurons of an organism are concentrated towards one end of the body. The neurons become concentrated in the head region and allows the brain of the organism to be situated in one place. Cephalization is beneficial because it allows a complex brain to be developed. Together with the bilateral body plan, a complex brain enables an organism to make complex and quick movements. A bilateral body plan is simply an arrangement of an organism’s body parts, which involves a front end (head) and a back end (like a tail).
The nervous system of primitive organisms is usually diffused and the neurons are spread out throughout the entire body. On the other hand, higher organisms such as human beings have their brains located at a single end of their body. Basically, cephalization is the process which enables organisms to have a brain. At an intermediate level of this process, organisms may also possess ganglia, which refer to groups of nerve cells or mini control centers that are scattered throughout their bodies.
Although the trend shows that advanced organisms undergo cephalization, this is not always the case. Some organisms which are considered evolutionarily advanced in several aspects do not undergo this process. An example of this includes the starfish, which is classified as an advanced organism but didn’t undergo cephalization. On the other hand, flatworms, annelids, and arthropods, including insects and crustaceans all underwent cephalization.
As mentioned, one of the main advantages of cephalization is that it allows the formation of a complex brain, which allows the organism to become smarter. Aside from that, a complex brain also enables the organism to survive better. When a complex brain is attached to a complex body, it will enable the organism to move in complex manners. These advanced and complex movements do not only help organisms when it comes to hunting, but are also useful in avoiding hunters.