Zoos divide opinion : there are those who think it is cruel to keep animals locked up while others believe zoos are essential for the survival of endangered species. To argue that zoos imprison animals is to misunderstand what zoos are about. Without zoos many of the creatures we love and admire would no longer exist. Every single day,over one hundred animal species vanish. Scientists predict that as early as 2050 one quarter of the Earth's species will become extinct. Some animals are in danger because they are hunted. Alarmingly, the population of tigers has already fallen by ninety-five percent. Other species are in danger because of a lack of food. For example, there are fewer than 1300 giant pandas left in the wild. Zoos have special breeding programmes to help those animals at risk. These breeding programmes are proving extremely successful. As Irene Shapiro from Zoo and Wildlife Support says, "the Puerto Rican Parrot has grown in numbers from just thirteen to about eighty-five and the Golden Lion Tamarin Monkey, which has almost ceased to exist twenty years ago, has been reintroduced back into the wild. " Unfortunately, not everyone understands this important role zoos play. For example, Brian Featherstone from the Anti-Zoo Forum says, "I can't believe we take animals from the wild and put them in cages for the entertainment of the public! We should view them on film or TV in their natural environment.,' However, this misses the point. A zoo does more than display animals to the public. It ensures their survival. Without zoos you would not be able to see many of these animals on TV or anywhere else! According to the writer ,the most important function of the zoo is to   _  .
make a lot of money entertain visitors ensure animals' survival educate the public