Why are invasive species dangerous to the environment?

They are dangerous to the environment because they have no natural competition. That being said they have nothing to keep their population in check, therefore, taking away food, and habits from all the other species. Thus, causing species to die out, which in turn ruins the food chain.

If you get a map and put the countries a states all together it forms all one piece you can also tell because of the earth quakes

Ican not answer this question since it does not have enough information