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
Close Flagella None
Close Chloroplast Reddish, numerous (from symbiont/prey)
Lifestyle Mainly Close photosynthetic Close (kleptochloroplastidic)
Close Bloom Dark red in colour, often found in coastal and Close upwelling regions
Harmful effects None known
Habitat Close Neritic and Close planktonic
Geographic Close Cosmopolitan, concentrated in coastal regions
Seasonal Present throughout the year, most abundant in spring and fall
Growth Conditions
Close Salinity 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 anterior lobe and a smaller Close posterior 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 nucleus 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 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
Close Silicate (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.