About three thousand years ago, a Chinese emperor kept a collection of animals in what he called an "intelligence part." If the emperor kept the animals alive to study them and learn something of their habits, then this was perhaps the first zoo, because today this is what a zoo is a large, enclosed area where wild animals, birds, and reptiles are kept for people to see and scientists to study.
Long ago it became a custom to keep animals at home. As time passed and villages and towns grew, some men kept wild animals in enclosures on their property.
In this way, they had animals on hand when they wanted to go hunting. Also, the animals could be taught amusing tricks to entertain people. But men often collected wild animals to show how rich and powerful they were. To make themselves popular, they sometimes allowed people to enter their parks and look at their animals.
There were public zoos in Europe as early as the 9th century. Many more were created in the larger towns and cities during the next 700 or 800 years.
A zoo's size is rated by the number of kinds of animals it contains. Only four zoos have more than one thousand kinds of animals. Of these, the largest is the San Diego Zoo in California.
Then come the West Berlin Zoo, the Bronx Zoo in New York City, and Belgium's Antwerp Zoo.
Most often, zoos buy animals from dealers. Many large animals are very expensive.
