SAO PAULO, Brazil (AP) ??? Seven rare albino alligators disappeared from a Brazilian university zoo and authorities suspect animal smugglers stole them, officials said Friday.

The theft at the Federal University of Mato Grosso was carried out sometime between Monday, when the alligators were last fed, and Wednesday morning, when a zookeeper noticed their disappearance, zoo director Itamar Assumpcao told The Associated Press.

There were no signs of a break-in, he added.

A federal police spokeswoman, who asked not to be identified because of departmental regulations said, "we believe they may have been stolen to be sold abroad or to animal smugglers here in Brazil."

Brazil accounts for about 15 percent of illegal animal trading worth $10 billion to $20 billion annual around the globe, according to Renctas, a Brazilian non-governmental organization that combats animal trafficking,.

The alligators are extremely rare and are worth about $9,700 apiece, the zoo director said.

"We know of no albino alligator born in the wild, probably because it would be impossible for it to survive," he said. "The lack of coloring would make it difficult if not impossible for them to hide from predators."

The albino alligators, born around 2005, are the result of 10 years of inbreeding that began shortly after a breeder sent the zoo a male and female alligator that were much lighter than their normal dark green color.

The thieves left behind one alligator, which belonged to the same brood as those stolen. Another two are currently at the Sao Paulo Aquarium, Assumpcao said.

--Stan Lehman, The Associated Press