During the period the sponges described herein were which were used only sporadically in the past and were collected (1963-7), the author was a Research Associate regarded as of marginal value until two decades ago, at the Department of Geology, University of Illinois, paleontology and embryology, are now receiving great participating in a research project on carbonate attention. They have already brought drastic revisions to sediments of the Bimini area, directed by Prof. William systematics, with regard to redefinition and classification W. Hay (Department of Geology, University of Illinois. of higher taxa. Other approaches have recently emerged utilizing biochemistry, histology, cytology, autecology, now at the Rosenstiel School of Marine and Atmospheric and zoogeography, and these promise significant ad Science, University of Miami) and supported by the National Science Foundation. The objective of this pro vance in the delimitation and classification oflower taxa. ject was a study of the relationship between the carbo The rapidly changing state of sponge taxonomy is reflect nate sediments of the Bimini area and the benthonic ed in the paucity of definitive (i. e. widely accepted) revisions of genera and families. The lack of stability and fauna and flora, especially with regard to skeletal ele ments contributed to the sediment.

During the period the sponges described herein were which were used only sporadically in the past and were collected (1963-7), the author was a Research Associate regarded as of marginal value until two decades ago, at the Department of Geology, University of Illinois, paleontology and embryology, are now receiving great participating in a research project on carbonate attention. They have already brought drastic revisions to sediments of the Bimini area, directed by Prof. William systematics, with regard to redefinition and classification W. Hay (Department of Geology, University of Illinois. of higher taxa. Other approaches have recently emerged utilizing biochemistry, histology, cytology, autecology, now at the Rosenstiel School of Marine and Atmospheric and zoogeography, and these promise significant ad Science, University of Miami) and supported by the National Science Foundation. The objective of this pro vance in the delimitation and classification oflower taxa. ject was a study of the relationship between the carbo The rapidly changing state of sponge taxonomy is reflect nate sediments of the Bimini area and the benthonic ed in the paucity of definitive (i. e. widely accepted) revisions of genera and families. The lack of stability and fauna and flora, especially with regard to skeletal ele ments contributed to the sediment.

In the course of the last century a considerable amount of scientific work has been carried out in the Cayman Islands. The results of this (outlined in Chapter 1) are widely distributed in unpublished reports, university theses, various scientific publications and books, many of these sources being difficult to find and some now unobtainable. The purpose of this book, therefore, is to bring all this scattered information together and to present a coherent account of the biogeography and ecology of the Islands, as an easily available reference source and as a foundation on which future work can be based.

With contributions by E.Abraham, D.Barnes, R.Carpenter, L.Collado, P.Dodds, S.Dudgeon, D.Garbary, S.Gatti, B.Helmuth, M.R.Koehl, H.Lasker, R.Merks., W.Müller, S.Muko, B. Rinkevich, J.Sanchez, P.Sloot, M.Vermeij

Life began in the sea, and even today most of the deep diversity of the planet is marine. This is often forgotten, especially in tropical countries like Costa Rica, renowned for their rain forests and the multitude of life forms found therein. Thus this book focusing on marine diversity of Costa Rica is particularly welcome. How many marine species are there in Costa Rica? The authors report a total of 6,777 species, or 3. 5% of the world’s total. Yet the vast majority of marine species have yet to be formally described. Recent estimates of the numbers of species on coral reefs range from 1–9 million, so that the true number of marine species in Costa Rica is certainly far higher. In some groups the numbers are likely to be vastly higher because to date they have been so little studied. Only one species of nematode is reported, despite the fact that it has been said that nematodes are the most diverse of all marine groups. In better studied groups such as mollusks and crustaceans, reported numbers are in the thousands, but even in these groups many species remain to be described. Indeed the task of describing marine species is daunting – if there really are about 9 million marine species and Costa Rica has 3. 5% of them, then the total number would be over 300,000. Clearly, so much remains to be done that new approaches are needed. Genetic methods have en- mous promise in this regard.

Research whilst compiling this book has uncovered a fauna about twice the size as that previously published in the literature and consequently Systema Porifera revises and stabilizes the systematics of the phylum to accommodate this new knowledge in a contemporary framework. Practical tools (key illustrations, descriptions of character) are provided to facilitate the assignment of approximately 680 extant and 100 fossil genera. Systema Porifera is unique making sponge taxonomy widely available at the practical level of classification (genera, families, order). It is a taxonomic revision of sponges and spongiomorphis (such as sphinctozoans and archaeocyathans) based on re-evaluation of type materials and evidence. It is also a practical guide to sponge identification providing descriptions and illustrations of characters and interpretation of their importance to systematics. Systema Porifera addresses many long standing nomenclatural problems and provides a sound baseline for future debate on sponges and their place in time and space. Systema Porifera describes 3 classes, 7 subclasses, 24 orders, 127 families and 682 valid genera of extant sponges (with over 1600 nominal generic names and an additional 500 invalid names treated). Treatment of the fossil fauna is less comprehensive or critical, although 6 classes, 30 orders, 245 families and 998 fossil genera are mentioned. Keys to all recent and many fossil taxa are provided.