Stephanopyxis turris

General Close


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

Shape Pill-shaped; cylindrical to spherical
Size Length 20 - 100 μm, diameter 36 - 57 μm
Colour Yellow-brown
Connection 12 - 16 Close


In some diatoms, "closed or solid structures projecting from the cell wall;" in dinoflagellates, solid projections that usually taper to a point.

connected midway
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.

Numerous, 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. Close

Resting spore

In diatoms, a cell that requires a dormancy period prior to germination and can survive for several years; usually developed to survive adverse conditions. They are commonly observed in centric but not pennate diatoms. The morphology of the spore may be similar or different from a vegetative cell; they usually have heavily silicified walls and are rich in storage products (Horner 2002).

Resting spore


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 May hinder egg production in copepods
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 Temperate to subtropical
Seasonal Usually more abundant in spring and summer
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).

31 - 36
Temperature 7 - 21 °C


Melosira costata Greville 1866 Close


The original name for an organism. In botany, the original published nomenclature from which a new binomial nomenclature is derived for a particular group of organisms (Tindall 1999).

) (Guiry 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Subphylum Khakista
Class Coscinodiscophyceae
Subclass Coscinodiscophycidae
Order Melosirales
Family Stephanopyxidaceae
Genus Stephanopyxis
Species S. turris (Greville) Ralfs 1861

(Guiry and Guiry 2012)


Photosynthetic. Reproduces sexually and asexually (Guiry 2011). Resting spores are present and are Close


Originating from within an organism. Opposite of exogenous.

" (Hasle and Syvertsen 1997).


Cells are pill-shaped, from roughly cylindrical to almost spherical, and are usually connected in straight chains. The Close


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

surface is covered in coarse hexagonal Close


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

that are all similar in size. No Close

Intercalary bands

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

intercalary bands
are present. Adjacent cells are connected by numerous subcentral (not Close


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

) hollow spines, with a distinct line of fusion between adjacent spines. Spines are also slightly widened at the point of connection. Chloroplasts are numerous and discoid (Cupp 1943). Cells are yellow-brown in colour (Guiry 2012).
Cell Close


In a eukaryotic cell, a gel-like substance within the cell membrane that contains all the organelles except for the nucleus.

extends into the hollow spines and touches the cytoplasm of the neighbouring cell (Cupp 1943). "Resting spores with thick walls and strong spines at two consecutive ends of adjacent cells" (Cupp 1943).


Length 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
): 20 - 100 μm
Diameter (valvar axis): 20 - 90 μm
Areolae: 3.5 - 5 in 10 μm

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
: 12 - 16
(Cupp 1943, Kraberg et al. 2010)

Similar species

Other Stephanopyxis species. The spines of S. nipponica do not join midway, and S. palmeriana has areolae that are larger near the centre of the valves (Hasle and Syvertsen 1997).

Harmful effects

May hinder egg production in copepods (Poulet et al. 2007).


Neritic (Cupp 1943).


Temperate and subtropical species (Cupp 1943).
More abundant in late spring or early summer in Northern European waters (Kraberg et al. 2010). Often forms spring blooms and occasionally present in the summer around the UK (Jones and Spencer 1970).
"Fairly common, but never abundant off southern California and in Gulf of California" (Cupp 1943).

Growth conditions

Information not available.

Environmental Ranges

Depth range (m): 0 - 148
Temperature range (°C): 6.776 - 21.472
Nitrate (μmol L-1): 0.567 - 9.600
Salinity: 31.144 - 36.128
Oxygen (mL L-1): 5.035 - 7.455
Phosphate (μmol L-1): 0.132 - 1.129

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).

(μmol L-1): 0.754 - 19.032
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Information not available.


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). 2012. Stephanopyxis turris. Accessed 07 Jan 2012.

Guiry, M. D. 2012. Stephanopyxis turris (Greville) Ralfs ex Pritchard, 1861. Accessed 07 Jan 2012.

Guiry, M. D. and Guiry, G. M. 2012. Stephanopyxis turris (Greville) Ralfs. Accessed 07 Jan 2012.

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.

Jones, M. and Spencer, C. P. 1970. The phytoplankton of the Menai Straits. ICES Journal of Marine Science. 33(2): 169-180.

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

Ocean Biogeographic Information System (OBIS). 2012. Stephanopyxis turris. Accessed 07 Jan 2012.

Poulet, S. A., Cueff. A., Wichard, T., Marchetti, J., Dancie, C. and Pohnert G. 2007. Influence of diatoms on copepod reproduction. III. Consequences of abnormal oocyte maturation on reproductive factors in Calanus helgolandicus. Marine Biology. 152(2): 415-428.

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