Systema Porifera: A Guide to the Classification of Sponges

Edited by:
  • John N. A. Hooper &
  • Rob W. M. van Soest
Kluwer Academic/Plenum: 2002. 1,810 pp. $595, £398, €625
Hanging on: some 15,000 species of sponge, including Leucetta chagosensis shown here, are alive today.

Sponges are “among the most successful life forms that have ever existed, with an estimated 15,000 species alive today”, according to the editors of this new work on their classification. The study of sponges has provided information about fundamental biological issues, including the biosynthesis of chemicals, totipotency (the ability of a cell to differentiate into other cell types), the evolution of eukaryotic immunology, and cellular theory. Sponges are also a source of therapeutic drugs, and can serve as biomarkers of pollution and proxies for palaeoclimatic change.

Nomenclature problems have plagued sponge taxonomists for over a century, however. The classification of sponges is complicated by their plasticity of form. They lack recognizable organs, cell types often migrate, and detritus (including skeletal parts called spicules from other sponges) can be incorporated, transforming the sponges beyond recognition. As a result there are many synonyms, which are difficult to reconcile with species descriptions (from different authors at different localities at different times) and with type material that is dispersed among museums around the world.

Systema Porifera attempts to resolve the higher systematics of the phylum Porifera, incorporating spongiomorphs such as the Archaeocyatha, 'Stromatoporoidea' and 'Sphinctozoa', which previously resided in other phyla. The book represents the work of 45 researchers, who took 7 years to re-evaluate and define the 2,100 nominal genera. It also provides a review of the taxonomic literature, creating an invaluable database of sponge biodiversity and a platform for the future development of sponge systematics.

Interest in sponges has been growing since the 1960s, when the discovery of bioactive metabolites (used to synthesize compounds with antibiotic and other biomedical properties) caught the attention of drug-development agencies. Since then, the number of recognized species of sponge has doubled, and today they are studied by several hundred researchers in various institutes around the world. This increase has led to an explosion in the discovery and documentation of species, which until now was dispersed in journals and monographs. Systema Porifera provides an important service by drawing information from these disparate sources together and updating it.

The editors are well qualified to do this because of their work on the rich sponge faunas of the Indo-Malay Archipelago. John Hooper has also revised the systematics of Australasian sponges, and Rob van Soest has concentrated on sponges from the northeastern Atlantic and the Caribbean. Together they have done an excellent job, making Systema Porifera interesting and accessible to a wider scientific audience than pure sponge taxonomists.

Descriptions of each class, order and family of sponge are organized under a series of uniform subheadings, making information easy to locate. Bibliographies are comprehensive and include many recent reviews. The authors discuss the history of nomenclature and classification, and recognize the possibility of future taxonomic changes, highlighting the fact that sponge science is still evolving.

Most sections contain an identification key for families and genera — something never previously attempted for Porifera — although I would recommend, as the editors suggest, referring to the Thesaurus of Sponge Morphology, edited by Nicole Boury-Esnault and Klaus Rützler (Smithsonian Contributions to Zoology 596, 1–55; 1997), to use them. Some diagrams and electron micrographs in Systema Porifera are a bit small, although enlarging them would have further increased the size of this already enormous — but invaluable — book.