Flat worms:

http://faculty.fmcc.suny.edu/mcdarby/animals&plantsbook/animals/03-Flatworms.htm

Round worms:

http://faculty.fmcc.suny.edu/mcdarby/animals&plantsbook/animals/04-Roundworms.htm

Cnidarians:

http://animals.about.com/od/cnidarians/p/cnidaria.htm

Annelid worms:

http://www.infoplease.com/encyclopedia/science/annelida-annelid-characteristics.html

Mollusks:

http://molluscs0.tripod.com/id1.html

Ecinoderms:

http://www.starfish.ch/reef/echinoderms.html

http://www.earthlife.net/inverts/cnidaria.html

http://www.earthlife.net/inverts/platyhelminthes.html

http://www.mcwdn.org/Animals/Roundworms.html

http://www.ento.csiro.au/education/allies/annelida.html

http://www.oceanicresearch.org/education/wonders/mollu
sk.html

http://tolweb.org/Echinodermata