Demospongiae (Sponges)
Brief descriptions about sponges and their natural history.
Introduction to Porifera
A good start on the biology of sponges, including phylogeny, life history, and ecology.
Sponges
Includes information about sponges such as growth, enemies, and appearance.
The Shape of Life: Porifera
Introduction to the phylum, including photographs, classification, and habitat.