Rhizosolenia setigera

General Close



Shape Cylindrical
Size Length 100 - 500 μm, width 4 - 20 μm
Colour Yellow-brown
Connection None (solitary)
Covering Silica Close









Many small elliptical chloroplasts
Lifestyle Close



. Sexual/asexual.



Shallow water Close


"Enclosed areas along the shoreline where freshwater from groundwater and streams is mixed with salt water from the surrounding oceans" (McCaffery and Livingston 2000).

Harmful effects Produces toxins and causes Close


Describing a condition where there is no available oxygen for primary production. Oxygen may be present in complexed forms that are not available for phytoplankton. A related term is hypoxia, where oxygen is present at very low concentrations.

Habitat Close



, Close


Of or relating to estuaries.

and oceanic
Geographic Close


Widely distributed; occurring in many parts in the world.

except in polar waters
Seasonal Late spring to early fall
Growth Conditions



24 - 36
Temperature -2 - 30 °C


Rhizosolenia japonica Castracane 1886
Rhizosolenia hensenii Schuett 1900
Pyxilla baltica Grunow 1881
Rhizosolenia pungens Cleve-Euler 1937
Rhizosolenia crassispina Schroeder
(EOL 2011)


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Heterokonta
Phylum Ochrophyta
Class Coscinodiscophyceae
Subclass Rhizosoleniophycidae
Order Rhizosoleniales
Family Rhizosoleniaceae
Genus Rhizosolenia
Species R. setigera Brightwell 1858

(Guiry and Guiry 2011)


Rhizosolenia setigera is an Close


An organism that can use inorganic materials for primary production of complex organic compounds by practicing photosynthesis or chemosynthesis. For example, plants are autotrophic organisms.

centric diatom (Smithsonian 2012). It has both sexual and asexual cycles of reproduction (Guiry and Guiry 2011). R. setigera produces 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 spores
, which are completely different from the mother cell (Horner 2002). Resting pores are torpedo-shaped and are formed in pairs (Smithsonian 2012).


Cells are cylindrical, with conical Close



narrowing into a long, straight and needle-like Close


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

(Horner 2002, LUMCON 2012). Cells are much longer than they are wide and valves do not have Close


(plural: otaria) In Rhizosolenia and related diatoms, an elongated, membranous thickening of the cell wall near the base of an external process. Otaria were previously called "wings" and can be seen as small lobes at the base of the needle-like spine at each end of a Rhizosolenia cell (Hasle and Syvertsen 1996).

(EOL 2011). Cell frustule is weakly Close


Describing the character (i.e., white, shimmery) or chemical presence silicon dioxide (SiO2) as a component of phytoplankton cell covering.

. R. setigera cells are wider in the centre and gently narrow towards either end (Hasle and Syvertsen 1996). Cell has many chloroplasts located through out the cell (Smithsonian 2012). Cells are often solitary (Horner 2002).


Length: 100 - 500 μm
Diameter: 2 - 50 μm
(Horner 2002)

Similar species

Rhizosolenia pungens is believed to be a variety of R. setigera. The R. setigera cell gradually narrows into a needle-like spine (Smithsonian 2012). R. pungens abruptly narrows into a spine (Smithsonian 2012). R. setigera produces resting spores, but R. pungens does not (Smithsonian 2012).

Harmful effects

Produces chemicals (monocyclic alkenes) that might cause mortalities of marine organisms due to oxygen depletion during bloom decay (EOL 2011).


Mainly coastal and estuarine, though occasionally found in open oceans (EOL 2011).


R. setigera is Close


Describing organisms that are able to withstand a wide range of temperatures in the environment.

(found in temperatures ranging from -2 - 30 °C) and Close


Describing organisms that are able to withstand a wide range of salinities in the environment (e.g., fresh, brackish, salt).

(found in salinity ranging from 1.5 - 37; EOL 2011). It is considered to be a north temperate species but has been seen throughout the world's oceans from tropical to cold temperate waters (Smithsonian 2012). R. setigera is not found in polar waters (EOL 2011).

Environmental Ranges

Depth range (m): 0 - 270
Temperature range (°C): -1.765 - 29.468
Nitrate (μmol L-1): 0.053 - 15.539
Salinity: 24.029 - 35.840
Oxygen (mL L-1): 4.444 - 9.192
Phosphate (μmol L-1): 0.046 - 1.696

Silicic acid


(μmol L-1): 0.648 - 37.729
(EOL 2011)

Bloom characteristics

Blooms in shallow water embayments in late spring and early fall (Haigh 2010, Horner 2002).


Encyclopedia of Life (EOL). 2011. Rhizosolenia setigera Brightwell 1858. http://www.eol.org. Accessed 11 Sept 2011.

Guiry, M. D. and Guiry, G. M. 2011. Rhizosolenia setigera Brightwell 1858. http://www.algaebase.org. Accessed 09 Sept 2011.

Haigh, N. 2010. Harmful Plankton Handbook. Nanaimo, BC. Canada. 53.

Hasle, G. R. and Syvertsen, E. E. 1996. Marine Diatoms. Tomas, C. R. (ed.) Identifying Marine Phytoplankton. Academic Press, Inc., San Diego, 531.


Louisiana University Marine Consortium (LUMCON). 2012. Rhizosolenia setigera Brightwell 1858. http://phytoplanktonguide.lumcon.edu/display.asp?dtype=organism&id=258. Accessed 21 Jan 2012.

Smithsonian Institution. 2012. Rhizosolenia setigera Brightwell 1858. http://www.sms.si.edu/irlspec/Rhizos_setige.htm. Accessed 21 Jan 2012.

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