If you think alien invasions are just a subject of science fiction movies, think again. Read about how living creatures hitch rides on ships and travel to new ecosystems, heavily impacting – and often destroying – these new ecosystems. This is the story of the Zebra and the Quagga mussel, traveling thousands of miles to invade Lake Michigan. Learn how these invaders changed the lake ecosystem, and then research other invaders to learn about how they can be so successful in a new environment.