Other
Coe College: Hermit Crab Sponges
An interesting article about a kind of sponge that a hermit crab carries around on its back.
University of California
Ucmp: Phylum Porifera
Click on the name of the class of sponge you want to know about, and you'll see a picture and a description of it.
A-Z Animals
A Z Animals: Animal Facts: Sponge (Demospongiae)
This entry identifies the defining characteristics of the demospongiae, more commonly known as the sponge.
National Health Museum
Access Excellence: Carnivorous Sponge
Read about this startling discovery of a species of sponge that is not a filter feeder like all other sponges, but is actually carnivorous. Strange!