Hermit Crab Sponges - An article by Floyd Sandford about the sponges that are carried around by hermit crabs. www.public.coe.edu/departments/Biology/hermit.html
Introduction to Porifera - A good start on the biology of sponges, including phylogeny, life history, and ecology. www.ucmp.berkeley.edu/porifera/porifera.html
Phylum Porifera (Sponges) - Description of the sponges and their taxonomy, from the Animal Diversity Web. animaldiversity.ummz.umich.edu/porifera.html
Phylum Porifera - Pore-bearing animals - Description of the phylum, including descriptions of its constituent taxonomic classes, with photos of a few representative species. www.teaching-biomed.man.ac.uk/bs1999/bs146/biodiversity/porifera.htm
Porifera Biology on the WWW - A central clearinghouse for sponge researchers, including a porifera listserver bulletin board and who's who in sponge research. www.mailbase.ac.uk/lists/porifera/files