Animal Diversity Web: Porifera - Sponges
Sponges are a diverse group of sometimes common types, with about 5000 species known across the world. Sponges are primarily marine, but around 150 species live in fresh water. Sponges have cellular-level organization, meaning that that their cells are specialized so that different cells perform different functions, but similar cells are not organized into tissues and bodies are a sort of loose aggregation of different kinds of cells. This is the simplest kind of cellular organization found among parazoans.
Publisher - University of Michigan
Subjects - Poriferahttp://animaldiversity.ummz.umich.edu/accounts/Porifera/
Citation: Myers P. 2001. Animal Diversity Web: Porifera - Sponges. Ann Arbor, MI: University of Michigan. http://animaldiversity.ummz.umich.edu/accounts/Porifera/