http://schools.dcsdk12.org/education/components/scrapbook/default.php?sectiondetailid=62736
http://www.enchantedlearning.com/subjects/foodchain/glossary.shtml
http://www.actionbioscience.org/environment/esa.html
http://www.picadome.fcps.net/lab/currl/food_chain/default.htm
http://www.enchantedlearning.com/biomes/
http://elcerritowire.com/4/ecosystems.htm
http://dotearth.blogs.nytimes.com/2009/10/13/giant-snakes-pose-high-risk-to-us-ecosystems/