Federal officials have banned the importation and state-to-state movement of four large constrictor snakes they fear could become the next species to invade the Everglades.

The U.S. Fish and Wildlife Service announced the prohibitions on the reticulated python, DeSchauensee's anaconda, green anaconda and Beni anaconda Friday at a wildlife refuge in Florida.

It was the result of years of debate that led to similar restrictions three years ago on the Burmese python and three other large snakes.

One notable snake was left off the list: boa constrictors. It was the only other snake officials had considered including, but they ultimately decided so many people have boas as pets that such a ban would be ineffective.