Coscinodiscus granii

General Close


(diatoms) Having radial symmetry, i.e., cell is shaped like a coin or a tuna can or a soup can.

Shape Wedged cylindrical disc
Size Diameter 40 - 200 μm, height 30 - 180 μm
Colour Yellow-brown
Connection None (solitary)
Covering Silica Close


In diatoms, the hard and porous silica cell wall (Horner 2002).



(plural: flagella) A tail-like projection that sticks out from the cell body and enables movement.



An organelle in the cell that contains the cell pigments (Horner 2002). This is where photosynthesis occurs. A chloroplast is a specialized chromatophore.

Smooth and Close



Lifestyle Close


The chemical process by which light energy, water and carbon dioxide are combined to produce oxygen and organic compounds. Photoautotrophic organisms (plants and algae) use this reaction to produce their own food.

. Sexual/asexual.


A rapid increase or accumulation of algal populations in an aquatic system. This will likely involve one or a few dominant phytoplankton species. This follows seasonal patterns (i.e., spring, summer or fall bloom) with dominant species being those that are best adapted to the environmental conditions of that time period. Discolouration of the water may be observed because of the algae's pigmentation. Blooms are often green but may be yellow-brown or red depending on the species present.

Information not available
Harmful effects None known
Habitat Close


Describing shallow, near-shore areas and the organisms that live there. Refers to shallow marine waters ranging from the low tide mark to the continental shelf. Varying amounts of sunlight penetrate the water, allowing photosynthesis by both phytoplankton and bottom-dwelling organisms. Close proximity to land favours high nutrient content and biological activity (Encyclopedia Britannica 2011).

Geographic Close


Widely distributed; occurring in many parts in the world.

Seasonal Blooms in autumn in the Baltic Sea
Growth Conditions


The dissolved ion content of a body of water. Can be measured in the following units: parts per thousand (PPT or ‰), practical salinity units (PSU), and absolute salinity (g/kg). PPT is measured by weight, denoting the number of parts salt per thousand total parts or a value of 10-3. PSU measures the conductivity of saltwater and compares it in a ratio to a standard KCl solution (because this is a ratio, salinity measured in this way can also be written without units). The newest unit of salinity is absolute salinity, which uses the mass fraction of salt in seawater (g salt per kg seawater) rather than its conductivity (TEOS-20 2010).

34 - 36
Temperature 14 - 29 °C




Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Coscinodiscales
Family Coscinodiscaceae
Genus Coscinodiscus
Species S. granii Gough 1905

(Guiry and Guiry 2011)


Photosynthetic. Reproduces sexually (Schmid 1995) and asexually.


Cells are discoid and wedge-shaped, visible in Close


In diatoms, the portion of the cell wall between the two valves of a cell; made up of intercalary bands (bands closest to the valves) and connecting bands (bands in the middle of the girdle). In dinoflagellates, the equivalent of a cingulum or transverse furrow (Horner 2002).

view with one side higher than the other (may not be visible in all orientations). Close


In diatoms, the structurally distinct halves of the cell wall (Becker 1996).

are most convex at the tallest part of the cell, near one end of the cell. Cells have a rosette of larger Close


In diatoms, the regularly repeated hexagonal holes on the valve walls (HPP 2003).

at the centre of the valve. Chloroplasts are smooth and disc-shaped (Hasle and Syvertsen 1997). Cells are yellow-brown in colour.
"About 8 areolae in 10 μm near centre, 10 midway to Close


The outline or border that defines the shape of an organism or cell.

, and 11 near margin; on edge of valve Close


In diatoms, "the part of a valve that extends from the valve face, forming the valve edge." It is visible when the frustule is viewed in girdle view (Spaulding 2010).

13 in 10 μm. Chamber openings small, dotlike. Outer closing membrane of areolae very delicately Close


A simple hole through the surface of a diatom valve (Smithsonian 2011).

. Close


(symmetry) Describing a shape that many axes of symmetry. That is, it does not have a left and right like humans do (bilateral symmetry), but can be divided into equal halves no matter where you place the axis. Some examples of radially symmetrical organisms include sea stars and centric diatoms like Thalassiosira.

rows and secondary spiral rows distinct. Marginal Close


(plural: spinulae) A small spine or hook.

and the Close


Resembling glass; transparent or translucent.

lines radiating from the spinulae toward the center distinct, 5 - 7 μm apart. Two small Close


A natural projection or appendage on an organism.

or Close


(plural: apiculi) Short, sharp, but not stiff projections (Kuo 2006).

on margin at distance of about 120° from each other. Girdle formed from the two similar Close

Girdle bands

The connecting elements between two valves of a diatom cell. "They enclose and protect the cell and also accommodate the increase in cell volume during the cell cycle" (Horner 2002).

girdle bands
. No Close

Intercalary bands

Girdle bands that are furthest away from the valve (Smithsonian 2011).

intercalary bands
" (Cupp 1943).


In diatoms, a band next to the valve that may help link the valves together (Hasle and Syvertsen 1996).

wedge shaped, widest opposite to the opening. Radial Close


Often used to describe holes (areolae) on the valve surface of diatom frustules.

, incomplete Close


(referring to pores in diatoms) In diatoms, a striation or row of pores on the valve face. "In centric diatoms, striae may be radial, running from the centre of the valve to the margin ... In pennate diatoms, striae may be parallel to the median line of the valve or raphe" (Horner 2002).

, and Close


Intersecting to form an"X" shape.

arcs in the central part of the valve. Close

Cribrum (cribra)

(plural: cribrae) A perforated siliceous plate that blocks one of the many pores in a diatom's frustule (van den Hoek et al. 1995).

barely discernible with Close


(light microscopy) "Using a microscope in which a beam of light passes through optical lenses to view an image of the specimen" (MCM LTER 2010).

. One ring of Close

Marginal process

In some diatoms, a long, coarse external tube through the frustule (Tomas 1997).

marginal processes
including two larger processes around 135° apart, readily seen with LM; the larger processes seen as deep indentations of the valve mantle. Hyaline lines from the marginal processes toward the valve centre more or less distinct" (Hasle and Syvertsen 1997).


Diameter: 40 - 200 μm
Height Close

Pervalvar axis

The axis through the centre point of the two valves of a frustule. This axis is perpendicular to the valve face.

(pervalvar axis
): 30 - 180 μm at widest part (Kraberg et al. 2010)
Valve areolae: 8 - 11 in 10 μm
No. of bands/ Close


(plural: thecae) Cell wall. In dinoflagellates, it is composed of cellulose plates within vesicles (Horner 2002).

: 2
Valvocopula width: 17 - 20 μ
(Hasle and Syvertsen 1997)
Margin rings: 1
Areolae from margin: 3 - 4
Areolae apart: 2 - 5
(Hasle and Syvertsen 1997)

Similar species

Other species of Coscinodiscus and Thalassiosira. C. granii can be easily identified in girdle view due to its wedged shape. In valve view, this species can still be diagnosed as only one side of the valve would be in focus (Hasle and Syvertsen 1997).

Harmful effects

None known.


Neritic (Cupp 1943).


Cosmopolitan (Kraberg et al. 2010).
Forms characteristic autumn blooms in the Baltic Sea (Wasmund et al. 2003). Present throughout the year in "low to moderate" abundance, with higher concentrations in spring and summer in North European Seas (Kraberg et al. 2010).
"Not uncommon off California. Greatest abundance in Mission Bay near San Diego. North temperate or Close


Relating to the area immediately south of the Arctic.

species." (Cupp 1943).

Growth conditions

Tolerant of a wide range of temperatures (Kraberg et al. 2010) and salinities (Baudin 1980). Increased salinity and light intensity may promote sexual reproduction (Schmid 1995). Close

Silicic acid

A general term to describe chemical compounds containing silicon, oxygen and hydrogen with a general formula of [SiOx(OH)4-2x]n. Diatoms polymerize silicic acid into biogenic silica to form their frustules (Azam and Chisholm 1976).

uptake may be inversely correlated with light intensity to maintain a stable growth rate (Taylor 1985). May be more prone to parasite infections during summer to autumn months, when water temperatures range around 13 - 20 °C (Wetsteyn and Peperzak 1991). Also, potential blooms may be suppressed during turbulent conditions, where infections persistently keep concentrations low (Kühn and Hofmann 1999).
May be resistant to parasitic infections during high photosynthetic activity, either under stronger Close


Amount of solar energy per unit area on a surface (units: μE m-2 sec-1, where E is an Einstein, a mole of photons).

(Kühn 1998), or during conditions of high pH (above ∼8.8; Kühn and Köhler-Rink 2008).
Growth was inhibited when cadmium concentrations exceeded 20 μg L-1 (Rabsch and Elbrächter 1980).

Environmental Ranges

Depth range (m): 0 - 470
Temperature range (°C): 14.227 - 29.468
Nitrate (μmol L-1): 0.056 - 2.197
Salinity (PSU): 33.919 - 36.252
Oxygen (mL L-1): 4.500 - 5.952
Phosphate (μmol L-1): 0.062 - 0.279
Silicate (μmol L-1): 1.145 - 7.894
(OBIS 2011, cited in EOL 2011)

Bloom characteristics

Information not available.


Baudin, J. P. 1980. A contribution to the ecological study of Mediterranean brackish water systems. 2. Populations of the Citis lagoon (Bouches du Rhone). Vie et milieu. Paris. 30(3-4): 303-308.

Cupp, E. E. 1943. Marine Plankton Diatoms of the West Coast of North America. University of California Press. Berkeley, California. 238.

Encyclopedia of Life (EOL). 2011. Coscinodiscus granii. Accessed 8 Oct 2011.

Guiry, M. D. and Guiry, G. M. 2011. Coscinodiscus granii Gough. Accessed 8 Oct 2011.

Hasle, G. R. and Syvertsen, E. E. 1997. Marine diatoms. In: Tomas, C. R. (ed.) Identifying marine Phytoplankton. Academic Press, Inc., San Diego. 5-385.

Horner, R. A. 2002. A Taxonomic Guide To Some Common Phytoplankton. Biopress Limited, Dorset Press, Dorchester, UK. 200.

Kraberg, A., Baumann, M. and Durselen, C. D. 2010. Coastal Phytoplankton: Photo Guide for Northern European Seas. Verlag Dr. Friedrich Pfeil, Munchen, Germany. 204.

Kühn, S. F. 1998. Infection of Coscinodiscus spp. by the parasitoid nanoflagellate Pirsonia diadema: II. Selective infection behaviour for host species and individual host cells. Journal of Plankton Research. 20(3): 443-454.

Kühn, S. F. and Hofmann, M. 1999. Infection of Coscinodiscus granii by the parasitoid nanoflagellate Pirsonia diadema: III. Effects of turbulence on the incidence of infection. Journal of Plankton Research. 21(12): 2323-2340.

Kühn, S. F. and Köhler-Rink, S. 2008. pH effect on the susceptibility to parasitoid infection in the marine diatom Coscinodiscus spp. (Bacillariophyceae). Marine Biology. 154(1): 109-116.

Ocean Biogeographic Information System (OBIS). 2011. Coscinodiscus granii. Accessed 8 Oct 2011.

Rabsch, U. and Elbrächter, M. 1980. Cadmium and zinc uptake, growth, and primary production in Coscinodiscus granii cultures containing low levels of cells and dissolved organic carbon. Helgoland Marine Research. 33(1-4): 79-88.

Schmid, A. M. M. 1995. Sexual reproduction in Coscinodiscus granii Gough in culture: a preliminary report. Proceedings of the thirteenth International Diatom Symposium, Maratea, Italy, 1st-7th September 1994. 139-159.

Taylor, N. J. 1985. Silica incorporation in the diatom Coscinodiscus granii as affected by light intensity. British Phycological Journal. 20(4): 365-374.

Wasmund, N., Pollehne, F., Postel, L., Siegel, H. and Zettler, M. L. 2003. Biological state assessment of the Baltic Sea in 2002. Institut fuer Ostseeforschung, Warnemuende (Germany). 78.

Wetsteyn, L. P. M. J. and Peperzak, L. 1991. Field observations in the oosterschelde (The Netherlands) on Coscinodiscus concinnus and Coscinodiscus granii (Bacillariophyceae) infected by the marine fungus Lagenisma coscinodisci (Oomycetes). Hydrobiological Bulletin. 25(1): 15-21.

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