http://www.sheppardsoftware.com/content/animals/kidscorner/foodchain/producersconsumers.htm '
http://www.sheppardsoftware.com/content/animals/kidscorner/games/producersconsumersgame.htm%20
http://www.zephyrus.co.uk/foodpuzzlechain.html
http://www.harcourtschool.com/activity/food/food_menu.html
http://www.sheppardsoftware.com/content/animals/kidscorner/games/foodchaingame.htm
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/S/Symbiosis.html
http://www.botany.uwc.ac.za/sci_ed/grade10/ecology/symbiosis/commen.htm