My Sources
- http://hes.ucfsd.org/gclaypo/circulatorysys.html
- http://www.livescience.com/22486-circulatory-system.html
- http://www.infoplease.com/encyclopedia/science/annelida-annelid-characteristics.html
- http://thecircleofblood.weebly.com/annelida.html
- http://www.cals.ncsu.edu/course/ent425/tutorial/circulatory.html
- http://circulatoryswaggwagons.weebly.com/cnidaria.html
- http://www.innerbody.com/image/cardov.html