The Shanghai Zoo is overcrowded with exotic pets such as red-eared turtles and estuarine crocodiles that have been abandoned by their owners.

Officials said every time such an animal or reptile is found in the city, they would be sent to the zoo. People may abandon such pets when they decide it takes too much time or money to raise them.

The zoo now is caring for close to 80 red-eared turtles and doesn't have the space for any more, said Wu Weichun, director of the zoo's amphibian department.

"Almost all of them were abandoned somewhere in the city," Wu said. "We have to adjust the environment, such as temperature and relative humidity, to control their reproduction."

The zoo once received more than a dozen estuarine crocodiles. It had intended to establish a crocodile aid center, but most of the reptiles died last winter due to the cold weather.

Other pets sent to the zoo include green iguanas, snakes and other lizards. The latest green iguana arrived last month, when one was found in Jiading District.

Wu said raising a green iguana is rather costly because the reptile, which lives in tropical rain forests in the wild, needs extra ultraviolet light. Zookeepers also have to feed it often.

Experts said these exotic animals and reptiles have a strong ability to reproduce and may threaten native Shanghai species.

In other cases, some species may not survive long as they can't adapt to the city's environment.

"People should think it over before buying such pets," said Pei Enle, director of the Shanghai Wildlife Protection Center. "Otherwise it's unfair to the animals, and can be harmful to the ecological balance if they are set loose."