INTRODUCTION

The bryozoans are filter feeding invertebrates, small and sessile; most of them marine and colonial. On the sea shores they can be found encrusting bivalve shells or snails, and they will look like a stain of different color similar to a sponge but solid. Or on the stones and shells left in the puddles at low tides. But being small and inconspicuous generally go unnoticed.

However the phylum Bryozoa have more than 6,000 living species described, its oceanic distribution is worldwide and are found from the intertidal zone to hundreds or thousands of meters deep in tropical and polar seas. Moreover, the fossil record extends to the Paleozoic 400 million years ago (Hayward y Ryland, 1979).

The individuals (zooids) that form the colonies of bryozoans consist on a boxlike exoskeleton of calcium carbonate less than one millimeter long. And within each one a fleshy part called polypide composed by the lophopore, digestive tract, gonads and nervous system (Soule et al. 1975).

The colonies varies in size and forms: they can be gelatinous or calcareous, encrusting, rigid erects or flexibles and articulated. In the eastern Pacific the majority are encrusting but there are some flexibles and articulated.

The first faunistic studies about bryozoans from Panamá date back 90-50 years; and were done by Anna B. Hastings (1929) in specimens collected in the coasts of Colón, and the gulfs of Panamá and Chiriquí. And Raymond C. Osburn (1950-1953) who included in his books encrusting specimens on oysters shells, provided by the United States Fish and Wildlife Service.

Between the years 1986 and 1996, 22 dredging collections and 11 in intertidal zones were made on the coasts and insular areas of the gulfs of Panamá and Chiriquí. And also were added the collections made in the same areas, during the years 2004 and 2005 by the scientists Priska Schäfer and Beate Bader of the University of Kiel, Germany. With the purpose to know the presence, abundance and diversity of bryozoans present in different substrates such as: rocks, coral rubble, shells, sediment concretions etc. These collection were dry preserved, i.e. were rinsed with water and allowed to dry.

To study the specimens they were cleaned with diluted sodium hypochlorite, which eliminate the soft tissues and allowed to better appreciate the micro sculpture (morphology) of exoskeleton, whose taxonomic features are most used to identify species. The best specimens were then sectioned from the substrate (shell, coral rubble, pebble) with a saw; to finally photographed with the scanning electron microscope which is the best instrument to study, describe and record the species of these marine invertebrates.

Our objective is to update the knowledge of the diversity and ecology of bryozoans Cheilostamate from the Pacific of Panama; and shared it with the scientific community and the public interested in science topics.

Amalia Herrera-Cubilla

I have a Degree in Biology with specialization in Zoology from the University of Panama. And PhD in Oceanology from the University of Aix-Marseille II, in France.

I have worked as a teacher at the Ministry of Education, and as a researcher at the Smithsonian Tropical Research Institute, with Dr. Jeremy Jackson.

During these last 25 years I have worked doing what I like most: Research in Ecology, Taxonomy and Evolution. And currently, I am Research Associate at the Smithsonian Tropical Research Institute.

Aknowledgements

Jeremy B. C. Jackson during the years as staff scientist in Marine Biology at the Smithsonian Tropical Research Institute the collections were made. Timothy Delaney made the collections on Isla Naos. We also received valuable logistical and field support from the Institute staff to make collections in the gulfs of Chiriquí and Panamá: Anibal Velarde, Felix Rodriguez, Marcos Alvarez, Javier Jara, Juan Mate, Axel Calderón. And the technical assistance of Jorge Ceballos with the scanning electron microscope. Priska Schäfer and Beate Bader of the Christian-Albrechts University in Kiel allowed us to include part of their collection. A. H. Cheetham and Jo Ann Sanner of the Smithsonian National Museum of Natural History provided us with photographs that helped identify the species of bryozoans present in this project, and were included in the data base.

References

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Cheetham, A. H., Sanner, J. y Jackson, J. B. C., 2007. Metrarabdotos and related genera (Bryozoa: Cheilostomata) in the Late Paleogene and Neogene of tropical America. Journal of Paleontology 81 Supplement 1: 1-91.

Hastings, A. B. 1929. Cheilostomatous Polyzoa from the vicinity of the Panama Canal collected by Dr. C. Crossland on the cruise of the S.Y. "St George". Proceedings of the Zoological Society of London 1929: 697-740.

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Winston, J. E. 2005. Re-description and revision of Smitt's "Floridan Bryozoa" in the collection of the Museum of Comparative Zoology, Harvard University. Virginia Museum of Natural History Memoir Number 7: x, 1-147. (with an annotated catalogue of specimens collected by L.F. de Pourtalès in Florida and Carolina, housed at the Museum of Comparative Zoology, Harvard University)