Coscinodiscus centralis

Classification
General Close

Centric

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

Centric
diatom
Description
Shape Cylindrical, Close

Discoid

Disc-shaped.

discoid
Size Diameter 100 - 300 μm
Colour Yellow-brown
Connection None (solitary)
Covering Silica Close

Frustule

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

frustule
Close

Flagellum

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

Flagella
None
Close

Chloroplast

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

Chloroplast
Small, numerous, plate-like
Behaviour
Lifestyle Close

Photosynthesis

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.

Photosynthetic
. Sexual/asexual.
Close

Bloom

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.

Bloom
Information not available
Harmful effects None known
Distribution
Habitat Oceanic
Geographic Close

Cosmopolitan

Widely distributed; occurring in many parts in the world.

Cosmopolitan
Seasonal Most abundant during monsoon season in southwest India
Growth Conditions
Close

Salinity

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).

Salinity
18 - 36
Temperature -2 - 25 °C

Synonym(s)


Coscinodiscus asteromphalus var. centralis Grunow 1884 Close

Heterotypic

A difference in type. In naming species, a heterotypic synonym is one that comes into being when a taxon becomes part of a different taxon. Compare to homotypic.

(heterotypic
)
Coscinodiscus oculus-iridis var. tenuistriata Grunow 1884 (heterotypic)
(Guiry and Guiry 2011)

Classification


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Coscinodiscales
Family Coscinodiscaceae
Genus Coscinodiscus
Species S. centralis Ehrenberg 1844

(Guiry and Guiry 2011)

Lifestyle


Photosynthetic. Reproduces sexually and asexually (Guiry 2011).

Description


Cells are discoid. Valves are slightly convex, with a distinct central rosette of large Close

Areola(e)

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

areolae
in a slight depression (Cupp 1943). Chloroplasts are small, numerous, and plate-like (Hasle and Syvertsen 1997). Cells are yellow-brown in colour (Guiry 2011).
"Areolae 3½ - 4 in 10 μm near center, 4 - 5 midway to Close

Margin

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

margin
, and 5 - 6 near margin. Close

Spinula

(plural: spinulae) A small spine or hook.

Spinulae
along margin 5 - 7 μm apart, placed a short distance in from margin. Three to four rows of areolae between spinulae. Spinulae often difficult to see in Close

Valve

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

valve
view. Close

Radial

(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.

Radial
lines from spinulae toward center indistinct. Two asymmetrical Close

Apiculus

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

apiculi
, sometimes difficult to see; in some specimens distinct. Two collarlike Close

Intercalary bands

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

intercalary bands
on each valve, the one nearer the valve broader than the other. Inner chamber openings distinct, outer membrane more or less strongly Close

Poroid

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

poroid
. Radial rows and secondary curved rows marked. Valve margin radially striated, 6 - 8 Close

Striae

(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).

striae
in 10 μm" (Cupp 1943).
"Areolae rows group into narrow bundles bordered by Close

Hyaline

Resembling glass; transparent or translucent.

hyaline
lines, distinct in weakly 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).

silicified
valves and indistinct in coarsely silicified valves. Close

Decussating

Intersecting to form an"X" shape.

Decussating
arcs in the central part of the valve. Hyaline lines associated with Close

Labiate process

In diatoms, a simple slit in the valve wall with two internal lips, one on each side of the slit. They can be useful in identification because they are positioned differently in different species (Horner 2002).

labiate processes
at the valve margin. Interstitial meshes present, identical with the pentagonal areola at the point of origin of an incomplete stria or an adjacent larger areola. 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).

Cribra
resolved with LM, consisting of one central pore and a marginal rings of pores. Close

Marginal process

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

Marginal processes
readily resolved with Close

LM

(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).

LM
; the smaller processes are long necked and slightly curved, and the two larger processes, around 135° apart, have two Close

Horns

The apical or antapical extensions found in some armoured dinoflagellates; they contain cytoplasm, are covered in thecal plates and can be hollow or partially solid (Horner 2002).

'horns
'" (Hasle and Syvertsen 1997).

Measurements


Cell:
Diameter: 100 - 300 μm
Valve areolae: 4 - 6 in 10 μm
No. of Close

Theca

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

bands/theca
: 3
Close

Valvocopula

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

Valvocopula
width: 20 - 24 μm
Close

Process

A natural projection or appendage on an organism.

Processes:

Margin rings: 1
Areolae from margin: 3 - 4
Areolae apart: 2 - 5
Scattered on valve face: no
(Hasle and Syvertsen 1997)

Similar species


Other species of Coscinodiscus and Thalassiosira. C. centralis can be distinguished by the large rosette in the centre of the valves.

Harmful effects


None known.

Habitat


Oceanic (Cupp 1943).

Distribution


Geographic: Cosmopolitan (Horner 2002).
Seasonal: Blooms found during monsoon season in southwest India (Sanilkumar et al. 2009).
Local: "Temperate to north temperate species" (Cupp 1943).

Growth conditions


Wide temperature tolerance (Horner 2002). May be favoured by low N:P and high Si:N ratios (Sanilkumar et al. 2009).

Environmental Ranges


Depth range (m): 0 - 470
Temperature range (°C): -1.743 - 24.625
Nitrate (μmol L-1): 0.360 - 18.305
Salinity (PSU): 17.940 - 36.252
Oxygen (mL L-1): 4.344 - 9.192
Phosphate (μmol L-1): 0.074 -1.717
Silicate (μmol L-1): 1.252 - 39.813
(OBIS 2011, cited in EOL 2011)

Bloom characteristics


Information not available.

References


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 centralis. http://eol.org/pages/912745/overview. Accessed 8 Oct 2011.

Guiry, M. D. 2011. Coscinodiscus centralis Ehrenberg, 1844. http://www.marinespecies.org/aphia.php?p=taxdetails&id=149159. Accessed 8 Oct 2011.

Guiry, M. D. and Guiry, G. M. 2011. Coscinodiscus centralis Ehrenberg. http://www.algaebase.org/search/species/detail/?species_id=37676. 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.

Ocean Biogeographic Information System (OBIS). 2011. Coscinodiscus centralis. http://www.iobis.org/mapper/?taxon_id=427593. Accessed 8 Oct 2011.

Sanilkumar, M. G., Padmakumar, K. B., Menon, N. R., Joseph, K. J., Sanjeevan, N. and Saramma, A. V. 2009. Algal blooms along the coastal waters of southwest India during 2005-08. Journal of the Marine Biological Association of India. 51(1): 69-74.


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