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What does a healthy ecosystem need?
A balance between prey and predators
How can alien invaders dangerous to an ecosystem?
They upset the balance of an ecosystem.
How did living things travel from one place to another millions of years ago?
By crossing land bridges between continents
Why did ecosystems stay in balance for most of Earth's history?
Because they could change GRADUALLY over time.
Who sped up the the pace (made it faster) of alien invasions?
Humans (!!!)
Name three things humans do that speed up the pace of alien invaders?
hunt, gather, farm
Which places are in big danger from alien invasions today?
islands (like Australia)
How do rabbits upset the native ecosystems in Australia?
They destroy soil, damage farmer's crops, and wreck (=destroy) the habitat of native species.
What is the name of the aggressive kind of bird imported to the US from England?
starling(s)
Where did the killer bees in Brazil originally come from?
Africa
How did zebra mussels travel from Europe to the United States?
on cargo ships (that have ballast tanks!)
Name three ways zebra mussels are harmful.
They sink buoys. They clog pipes. They eat the plankton, leaving the fish little food.
What did the US government do in the 1930s that sped up the spread of kudzu?
It hired hundreds of workers to plant kudzu (because they believed kudzu helped prevent soil from being washed away).
Why do kudzu plants grow faster in the southern part of the US than in Japan?
Because the climate there is warm and humid, which is good for kudzu.
How does kudzu damage forests?
It covers trees and makes it difficult for them to get sunlight.
Name one thing you can do to help solve the problem of alien invasion.
