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The silicoflagellate genus Distephanus ( Distephanopsis ). Robert Baldwin University Day April 14, 2010. What is a silicoflagellate ?.
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The silicoflagellategenus Distephanus (Distephanopsis) Robert Baldwin University Day April 14, 2010
What is a silicoflagellate? “Silicoflagellates are protists and claimed both by zoologists (as protozoans) and botanists (as algae). However, due to their autotrophic phytoplanktonic nature it is more logical to regard them as planktonic algae.” “The silicoflagellates are minute (20−50 µm, rarely up to 100 µm), unicellar, marine flagellates with a siliceous skeleton.” Bilal U. Haq et al., 1978 “The silicoflagellates are a group of planktonicprotists, exclusively marine, that contain chromatophores for photosynthesis. In that respect they are like other ‘algae’. They possess a single flagellum, presumably to maintain proper orientation to the sun for maximum efficiency in photosynthetic production. Unlike other “algae”, however, they also possess pseudopodia – a fact that led several early scholars to classify them as ‘animals’.” Richard T. Carter, 2008
How silicoflagellates are used Silicoflagellates are silica-secreting marine microplankton. “Recent revival of interest in the history of ocean basins and paleoclimates has enhanced their importance in paleooceanographic interpretations, especially in those areas where calcareous microfossils are either relatively scarce or completely lacking (e.g., in higher latitudes and deeper waters).” Bilal U. Haq et al., 1978 The carbonate compensation depth The reason why silica fossils are useful in deeper waters is because calcareous fossils dissolve below the calcite compensation depth. The calcite compensation depth (CCD), at the present time, is about 4200 to 4500 meters and can be 5000 meters deep in some places at the present time. It has not always been the same in the past. (Wikipedia)
Skeletal Terminology Figure 1. Maximum length = 65 microns. Richard T. Carter, 2007
Silicoflagellate descriptive terminology McCartney et al., 1990
Distephanus speculum has a hollow skeleton Y. T. Mandra
Distephanusspeculum with a double skeleton J. A. Barron
Pseudofibula Plexus map McCartney et al., 1993
pseudofibulid morphologies McCartney et al., 1990
The second column shows the minimum-distance configuration that connects all points (from Almgren and Taylor, 1976; Isenberg, 1976). McCartney et al., 1990
Scanning electron micrographs of specimens of the pseddofibula plexus from Leg 113, 100x. McCartney et al., 1990
Pseudofibula Plexusof Distephanus speculum speculum from ODP Leg 113 McCartney et al., 1990
Distribution of Dictyocha and Distephanus Dictyocha McCartney, 1995 Distephanus
Multiwindowed morphologies and some many sided types from ODP Leg 113 McCartney et al., 1990
Cretaceousgenera McCartney et al., 1990
Wide band indicates relative abundance > 50 %. • Narrow band denotes relative abundance = 10 %. • Line indicates a regular presence. • Small numbers refer to DSDP Leg. McCartney, 1987
Corbisematriacantha(Ehrenberg) McCartney et al., 1990
DictyochacalidaPoelchau, abapical view McCartney et al., 1990
Distephanusbolivensis McCartney et al., 1990
Distephanuspolyactis 1973
Cannopilushemisphaericus A Bachmann et al., 1963
Cannopilushemisphaericus A Bachmann et al., 1963
Cannopilussphaericus A Bachmann et al, 1963
Cannopiluspicassori A Bachmann et al., 1963
Cannopiluspicassori A Bachmann et al., 1963
References: Silicoflagellate: Distephanus speculum, showing hollow skeleton. Upper Miocene near San Felipe, Baja California. Upper specimen is about 60 microns from spine tip to tip. Scanning electron micrograph. From Y. T. Mandra and H. Mandra, Occasional Papers of the California Academy of Sciences, no. 99. Used with the permission of Y. T. Mandra, San Francisco State University. Silicoflagellate: Distephanus speculum with a double skeleton. Late Miocene. Lompoc, California. Length is 45 microns. Courtesy of J. A. Barron, U. S. G. S. http://www.cushmanfoundation.org/resources/slides/silmicros.html • Carbonate compensation depth (Wikipedia) • This page was last modified on 21 February 2010 • http://en.wikipedia.org/wiki/Carbonate_compensation_depth
