– Experts from the University of the Andes have detected the presence of the aggressive and exotic 'rana toro', or bullfrog (Rana catesbeiana) in some aquatic ecosystems of the Venezuelan Andes, particularly in the natural and artificial lakes of the northwestern state of Mérida. Considered one of the 100 worst invasive species, the bullfrog could push other amphibians into extinction because it successfully competes with them for food, feeding on insects, fish, crustaceans, as well as the larvae of other amphibians and even adult toads.