Fermi was referring to alien life. In the 4.4 billion years it took a species capable of space travel to form on Earth, Fermi proposed that the galaxy should have been overrun with intelligent ...

Naturalised species are alien species that form populations “that endure (maintain a reproductive population) for at least 10 years without direct intervention by people”, according to the ...

Alien species are species that are introduced to ... Among the more exotic are the fugu pufferfish, a form of rabbitfish known as the dusky spinefoot which is known among fishermen as an qawsalla ...

It can form dense mats and drive out native species ... In 2005, the Environment Ministry designated alligatorweed as an invasive alien species that poses a threat to local ecology and ...