http://universe-review.ca/R10-33-anatomy.htm#annelids
http://kidshealth.org/parent/general/body_basics/immune.html
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendocr.html
http://classic.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Animalia/Porifera/
http://www.emc.maricopa.edu/faculty/farabee/biobk/biobookendocr.html
http://classic.sidwell.edu/us/science/vlb5/Labs/Classification_Lab/Eukarya/Animalia/Porifera/