Monothalamous (single-chambered) foraminifera bearing mineral particles in their cytoplasm are a common component of the meiofauna in a range of shallow-marine settings and they are mainly represented by specimens of the genus Psammophaga. The etymology reflects the avid ingestion of sediment grains, which are retained in the cytoplasm as inclusions, while these foraminifera undergo normal biological activities. Samples for this study were collected from 5 transects, each with 3 stations, perpendicular to the coast in the central Adriatic Sea. They were collected in 5 pseudo-replicates for each station between 12–21 m water depth using a Van Veen grab in order to perform both sedimentological and morphological analyses. The specimens of Psammophaga were isolated from the upper 2–3 cm of surface sediments (3 replicates for each station) and selected individuals were prepared for Scanning Electron Microscopy. Surprisingly, the micrographs revealed the almost selective presence of few mineral types distributed within the cell body. To better identify the chemical composition of mineral grains ingested by Psammophaga, 10 specimens from 3 different stations were analysed using energy dispersive X-ray spectrometer (EDS) detector and related cartographies were produced. In association, the same type of investigation was made on the bulk and the finest fraction of the sediment from the same stations used for foraminiferal analyses in order to assess the distribution and the quantity of the minerals in the sediment. These preliminary analyses highlight the fine ability of Psammophaga to allocate particles of about the same size (~30-50 micron) and chemical nature inside their cell. This primitive and morphological simple foraminifer shows an evidence of extreme selection of minerals. The collection of the ingested material is probably a behavioural process; the organism must have some mechanisms, however simple, to pick up the appropriate types and sizes of particles which are much larger than the clay particles used for test construction.
Intracellular minerals in a single-chambered foraminifer.
MORIGI, CATERINA;
2013-01-01
Abstract
Monothalamous (single-chambered) foraminifera bearing mineral particles in their cytoplasm are a common component of the meiofauna in a range of shallow-marine settings and they are mainly represented by specimens of the genus Psammophaga. The etymology reflects the avid ingestion of sediment grains, which are retained in the cytoplasm as inclusions, while these foraminifera undergo normal biological activities. Samples for this study were collected from 5 transects, each with 3 stations, perpendicular to the coast in the central Adriatic Sea. They were collected in 5 pseudo-replicates for each station between 12–21 m water depth using a Van Veen grab in order to perform both sedimentological and morphological analyses. The specimens of Psammophaga were isolated from the upper 2–3 cm of surface sediments (3 replicates for each station) and selected individuals were prepared for Scanning Electron Microscopy. Surprisingly, the micrographs revealed the almost selective presence of few mineral types distributed within the cell body. To better identify the chemical composition of mineral grains ingested by Psammophaga, 10 specimens from 3 different stations were analysed using energy dispersive X-ray spectrometer (EDS) detector and related cartographies were produced. In association, the same type of investigation was made on the bulk and the finest fraction of the sediment from the same stations used for foraminiferal analyses in order to assess the distribution and the quantity of the minerals in the sediment. These preliminary analyses highlight the fine ability of Psammophaga to allocate particles of about the same size (~30-50 micron) and chemical nature inside their cell. This primitive and morphological simple foraminifer shows an evidence of extreme selection of minerals. The collection of the ingested material is probably a behavioural process; the organism must have some mechanisms, however simple, to pick up the appropriate types and sizes of particles which are much larger than the clay particles used for test construction.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
