Invasive species: Do they matter?

   Mass extinction--the (geologically) rapid disappearence of a sizeable fraction of the world's species--last occurred 65 million years ago.  That was the Cretacious-Tertiary (K-T) extinction, which wiped out the dinosaurs among other creatures.   It was caused, most likely, by an asteroid impact near today's Yucatan Peninsula, along with near simultaneous volcanic eruptions a world away in India.

   Now, scientists agree, we are in the middle of a new mass extinction.  Called the ``6th extinction'' because it is the sixth mass extinction of the last 600 million years,  What is causing this extinction?  We are.  In the words of a scientist from the American Museum of Natural History, ``We are our own asteroids.''

   Habitat loss is the main culprit.  They're not making any more habitat.  But we are making more people, more than 200,000 a day, worldwide.  They have to live somewhere, and in many places, such as New Jersey, habitats become homes.

   But another huge cause of the loss of biodiversity is the introduction of alien species to new habitats.  Often, alien species barely hang on and don't have much of an impact.  But too often, aliens disrupt native species and established ecosystems and when they do they are termed invasive. 

   In this WebQuest, you will research a variety of invasive species to help answer the following essential questions:

1.  What characteristics do invasive species have (Why do some species become invasive while others do not)?
2.  Why do invasives cause trouble?
3.  What can be done about invasives?