Myrionecta rubra

General Ciliate
Shape Roughly spherical with 2 lobes
Size Length 10 - 100 μm, width 20 - 75 μm
Colour Reddish
Connection None. Solitary
Covering None


(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.

Reddish, numerous (from symbiont/prey)
Lifestyle Mainly 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.



Describing a phytoplankton that steals the chloroplasts of a photoautotrophic phytoplankton. The former does not produce its own chloroplast, but keeps the "stolen" chloroplasts alive in order to photosynthesize. Thus, it is considered a mixotrophic organism because it is able to both photosynthesize and consume organic matter (pers. comm. J. Shiller).



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.

Dark red in colour, often found in coastal and Close


A wind-driven mechanism of mixing the water column. Cold, dense, nutrient-rich, and often oxygen-poor water from depths rises to replace the warmer nutrient-poor surface water. This input of nutrients can have a significantly increase primary productivity in a region (Dugdale 1985).

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).

and Close


Organisms that drift at the mercy of the currents.

Geographic Close


Widely distributed; occurring in many parts in the world.

, concentrated in coastal regions
Seasonal Present throughout the year, most abundant in spring and fall
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).

3 - 37
Temperature 15 °C (ideal)


Mesodinium pulex Bakker 1966
Cyclotrichium meunieri Powers 1932
Mesodinium rubrum Hamburger and Buddenbrock 1929
Halteria rubra Lohmann 1908
(Montagnes 2001)
*Still commonly referred to as Mesodinium rubrum.


Empire Eukaryota
Kingdom Chromista
Subkingdom Harosa
Infrakingdom Alveolata
Phylum Ciliophora
Subphylum Intramacronucleata
Class Litostomatea
Subclass Haptoria
Order Cyclotrichiida
Family Mesodiniidae
Genus Myrionecta
Species M. rubra Lohmann 1908

(Guiry and Guiry 2012)


Photosynthetic, but reported to also ingest cryptophytes. Kleptochloroplastidic (chloroplast-stealing) with an endosymbiont of cryptomonad origin (Gustafson et al. 2000).


Cell body is roughly spherical with a sub-equatorial constriction, separating the cell into a larger Close


The front. The part of the cell in the direction of movement. Opposite of posterior (HPP 2003).

lobe and a smaller Close


The back end of a cell. Opposite of anterior.

lobe. A belt of tufted hairs (cilia) is present in the constriction. Numerous red chloroplasts of the symbiont are distributed throughout the cell, while the symbiont Close


(plural: nuclei) In eukaryotic cells, a membrane-bound organelle that contains the cell's genetic information; the nucleus controls the activities of the cell by controlling gene expression.

is located centrally near the host nucleus. Cells are reddish in colour (Montagnes 2001).
Motile, with distinct sudden jumping movements spanning 10 to 20 times its body length, while staying motionless between jumps (Montagnes 2001).
When fixed with Close

Lugol's iodine solution

A solution of elemental iodine and potassium iodide in water; it was first used in 1829 by French physician Jean Lugol as a disinfectant. Lugol's iodine can be used as fixative to preserve phytoplankton samples for visual analysis at a later time (Leakey et al. 1994).

Lugol's iodine
solution this species normally is seen as a dark reddish-brown circular body surrounded by spiralling hairs (cilia).


Length: 10 - 100 μm
Width: 20 - 75 μm
(Taylor et al. 1971, Montagnes 2001)

Similar species


Harmful effects

None known (Montagnes 2001).


Neritic and planktonic, often near the water surface (Taylor et al. 1971).


Cosmopolitan, often concentrated in coastal regions (Taylor et al. 1971).
Present throughout the year, with higher concentrations in spring and fall at most locations (Taylor et al. 1971).
Present in the Strait of Georgia throughout the year, with higher abundances and occasional localized blooms in late spring and early fall.

Growth conditions

Tolerates temperatures of 0 - 24 °C and salinities of 3 - 37 (Montagnes 2001), with ideal temperatures around 15 °C (Taylor et al. 1971).
Vulnerable to sudden and rapid shifts in temperature and salinity (Taylor et al. 1971).

Environmental Ranges

Depth range (m): 0 - 68
Temperature range (°C): As low as -1.594
Nitrate (μmol L-1): 6.894 - 28.528
Salinity: Not available
Oxygen (mL L-1): 6.447 - 7.869
Phosphate (μmol L-1): 0.630 - 2.085

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): 4.938 - 75.352
(OBIS 2012, cited in EOL 2012)

Bloom characteristics

Waters with blooms of M. rubra are dark red in colour and easily observable with the naked eye. Often found in coastal waters and near zones of upwelling (Taylor et al. 1971).


Encyclopedia of Life (EOL). 2012. Mesodinium rubrum. Accessed 25 Apr 2012.

Guiry, M. D. 2012. Myrionecta rubra Lohmann, 1908. Accessed 25 Apr 2012.

Gustafson, D. E., Stoecker, D. K., Johnson, M. D., Van Heukelem, W. F. and Sneider, K. 2000. Cryptophyte algae are robbed of their organelles by the marine ciliate Mesodinium rubrum. Nature. 405: 1049-1052.

Montagnes, D. J. S. 2001. The Planktonic Ciliate Project Online - Myrionecta rubra. Accessed 25 Apr 2012.

Ocean Biogeographic Information System (OBIS). 2012. Mesodinium rubrum. Accessed 25 Apr 2012.

Taylor, F. J. R., Blackbourn, D. J. and Blackbourn, J. 1971. The red-water ciliate Mesodinium rubrum and its 'incomplete symbionts': A review including new ultrastructural observations. Journal Fisheries Research Board of Canada. 28(3): 391-407.

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