What is a "colonial animal" and what is Steinbeck's purpose in comparing a town to a colonial animal in The Pearl?

A town is a “colonial animal” because news travels so fast it seems to have a memory and motivation of its own.

When we are told that a town has “a nervous system and a head and shoulders and feet” it means that towns seem almost alive, like they are entities in themselves.  There are no two towns alike.  As long as there are people in the town who want to know something, news will...

A town is a “colonial animal” because news travels so fast it seems to have a memory and motivation of its own.

When we are told that a town has “a nervous system and a head and shoulders and feet” it means that towns seem almost alive, like they are entities in themselves.  There are no two towns alike.  As long as there are people in the town who want to know something, news will travel so fast and efficiently that it is almost as if the town itself is thinking and feeling.

And a town has a whole emotion. How news travels through a town is a mystery not easily to be solved. News seems to move faster than small boys can scramble and dart to tell it, faster than women can call it over the fences. (Ch. 3)

When Kino finds the pearl, this is big news in a tiny colonial town.  Such towns were close-knit communities, where everyone relied on everyone else and being in everyone else’s business was a way of life.  In other words, if you had something or did something important, everyone would know about it in about five minutes.  It’s small-town physics.  Everyone knows everyone’s life story.

Before Kino and Juana and the other fishers had come to Kino's brush house, the nerves of the town were pulsing and vibrating with the news - Kino had found the Pearl of the World. Before panting little boys could strangle out the words, their mothers knew it. (Ch. 3)

There are positives and negatives to people knowing everything as soon as it happens.  You have an audience no matter what.  They might be there to support you, or just curious.  The entire town seems to follow Kino to the doctor.  On the other hand, when everyone knows everything, that can be dangerous.  Someone might try to steal from you, especially if you have a very valuable pearl.