References: Addison, W. (2001, October 15). Earthworms. School of Arts & Sciences - University of Pennsylvania. Retrieved November 27, 2011, from http://www.sas.upenn.edu/~rlenet/Earthworms.html Carpi, A. (1999, May 18). Basic Anatomy - Organs & Organ Systems. Courses Pages. Retrieved November 27, 2011, from http://web.jjay.cuny.edu/~acarpi/NSC/14-anatomy.htm Devlin, E. (1990, July 19). Fetal Pig Dissection. people.hsc.edu. Retrieved November 27, 2011, from http://people.hsc.edu/faculty-staff/edevlin/edsweb01/new_page_14.htm Nale, M. (2004, September 8). The Crayfish Corner - Information. mackers.com. Retrieved November 27, 2011, from http://mackers.com/crayfish/info.htm Nowicki, S. (2010). Biology Grades 9-12 Holt McDougal Biology Florida... Orlando: Houghton Mifflin. T., D. (2011, November 3). Earthworm Body Systems. Informed Farmers. Retrieved November 27, 2011, from informedfarmers.com/earthworm-body-systems/
References: Addison, W. (2001, October 15). Earthworms. School of Arts & Sciences - University of Pennsylvania. Retrieved November 27, 2011, from http://www.sas.upenn.edu/~rlenet/Earthworms.html Carpi, A. (1999, May 18). Basic Anatomy - Organs & Organ Systems. Courses Pages. Retrieved November 27, 2011, from http://web.jjay.cuny.edu/~acarpi/NSC/14-anatomy.htm Devlin, E. (1990, July 19). Fetal Pig Dissection. people.hsc.edu. Retrieved November 27, 2011, from http://people.hsc.edu/faculty-staff/edevlin/edsweb01/new_page_14.htm Nale, M. (2004, September 8). The Crayfish Corner - Information. mackers.com. Retrieved November 27, 2011, from http://mackers.com/crayfish/info.htm Nowicki, S. (2010). Biology Grades 9-12 Holt McDougal Biology Florida... Orlando: Houghton Mifflin. T., D. (2011, November 3). Earthworm Body Systems. Informed Farmers. Retrieved November 27, 2011, from informedfarmers.com/earthworm-body-systems/