The alligators infected with the t-Virus experienced increased size, strength and aggression. The gator that Leon, Ada and Claire encountered grew to an enormous size, filling almost the entire sewer. The gator in the zoo grew only a bit larger, but still proved to be a formidable foe.
Both animals will attack any uninfected creature that comes near them. The sewer alligator did not show any hesitation to chase its victims on dry land, unusual since normal crocodilians often do not go very far from sources of water. The zoo crocodile on the other hand did not leave its lake home, but instead attempted to bite any victims near the lake shores or in the water.