Laboratory observations of benthic foraminiferal cysts

Abstract

Long-term observations on living benthic foraminifera in the laboratory were performed to investigate their behaviour and life style. We noticed that the formation of cysts or sedimentary envelopes is a common feature within many groups of foraminifera (organic walled, agglutinated and calcareous) in the laboratory. Several kinds of cyst were observed. In most cases, the entire foraminiferal shell was canopied with detritus or particles, but some specimens covered only parts of their body, such as the aperture region or pseudopods. Cysts were found attached to the glass walls of culture vessels or free in and on the sediment. Foraminifera stayed within cysts for hours to weeks. After leaving sedimentary envelopes, some specimens immediately started to build new ones, others not. The function of cyst formation observed in the present study was not clear, except one case where reproduction took place. Some monitored structures seemed not to be sedimentary cysts but unilocular agglutinated foraminifera with probably allogromiid-like organization. The formation of sedimentary envelopes seems to be a very basic character of foraminifera, suggesting a mechanism for the evolution of shells.

Keywords:

• Allogromiid-like structures
• benthos
• cysts
• laboratory observations
• live foraminifera
• sedimentary envelopes

Acknowledgments

We thank Wiebke Ruschmeier, Christina Schwarz and Bodo Rödiger for helpful support of the foraminifera cultures. Grateful thanks to the crews of F. S. Meteor and Tethys II for the good collaboration during several cruises. We are also indebted to the Laboratory of Marine Bio-Indicators on Yeu Island for the possibility to take samples and use the laboratory. We greatly appreciate the helpful comments of Tomas Cedhagen and one anonymous referee. This work received financial support from the Evangelisches Studienwerk e. V., Villigst, from the BMBF programme BIGSET (Biogeochemische Stoff- und Energietransporte in der Tiefsee, CH 03F 0177C), and from the Deutsche Forschungsgemeinschaft (DFG project, He 697/35-1), which are gratefully acknowledged.

Notes

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark

Present address: Laboratory of Geology, University of Angers, UPRES EA 2644, 2bd Lavoisier, 49045 Angers cedex 1, France.

Present address: Laboratory of Geology, University of Angers, UPRES EA 2644, 2bd Lavoisier, 49045 Angers cedex 1, France.

Additional information

Notes on contributors

Emmanuelle Geslin *

Published in collaboration with the University of Bergen and the Institute of Marine Research, Norway, and the Marine Biological Laboratory, University of Copenhagen, Denmark Present address: Laboratory of Geology, University of Angers, UPRES EA 2644, 2bd Lavoisier, 49045 Angers cedex 1, France.