the silicoflagellate genus distephanus ( distephanopsis )

The silicoflagellate genus Distephanus

(Distephanopsis)

Robert BaldwinUniversity DayApril 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 planktonic protists, 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

“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).”

Silicoflagellates are silica-secreting marine microplankton.

Bilal U. Haq et al., 1978

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)

The carbonate compensation depth

Figure 1. Maximum length = 65 microns.

Skeletal Terminology

Richard T. Carter, 2007

Silicoflagellate

descriptive terminology

McCartney et al., 1990

Y. T. Mandra

Distephanus speculum has a hollow skeleton

J. A. Barron

Distephanus speculum with a double skeleton

Pseudofibula Plexus

map



pseudofibulid morphologies


The second column shows the minimum-distance configuration that connects all points (from Almgren and Taylor, 1976; Isenberg, 1976).


Scanning electron micrographs of

specimens of the pseddofibula

plexus from Leg 113, 100x.

Pseudofibula Plexusof Distephanus speculum

speculum from ODP Leg 113


Distribution of Dictyocha and Distephanus

McCartney, 1995

Dictyocha

Distephanus


Multiwindowed morphologies

and some many sided types

from ODP Leg 113

Cretaceous genera


McCartney, 1987

Wide band indicates relative abundance > 50 %.

Narrow band denotes relative abundance = 10 %.

Line indicates a regular presence.

Small numbers refer to DSDP Leg.

Corbisema triacantha

(Ehrenberg)



Dictyocha calida

Poelchau, abapical

view

Distephanus bolivensis


Distephanus polyactis1973

Cannopilus hemisphaericus

A Bachmann et al., 1963

Cannopilus

hemisphaericus


Cannopilus sphaericus

A Bachmann et al, 1963


Cannopilus picassori

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

http://www.cushmanfoundation.org/resources/slides/silmicros.html

http://en.wikipedia.org/wiki/Carbonate_compensation_depth

http://en.wikipedia.org/wiki/Carbonate_compensation_depth

the silicoflagellate genus distephanus ( distephanopsis )

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