Provide information on the evolution of the neural system in animals.

(N/A) The neural system of all animals is composed of highly specialized cells called neurons.
It can receive,transmit,and detect various kinds of stimuli.
In lower invertebrates,the neural organization is very simple.
For example,in $Hydra$,it consists of a network of neurons. In insects,the neural system is better organized,where a brain is present along with a number of ganglia and neural tissues.
The vertebrates have a more developed neural system.
In higher organisms,the neural system performs three basic functions:
$(i)$ It receives sensory impulses from the external and internal environment and sends them to the brain.
$(ii)$ The brain analyzes the type of stimuli.
$(iii)$ Responses,according to the stimuli,are transported in the form of nerve impulses to various body parts or cells.