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Cool Facts About Cryptomonads!
Cool Facts About Cryptomonads!
Cryptomonads, like many eukaryotic algal lineages, obtained their plastids through the engulfment of a eukaryotic algal endosymbiont (a process known as secondary, or higher-order, endosymbiosis). Most eukaryotic algae eventually completely eliminated the nuclei of their endosymbionts, but Cryptomonads (along with one group of marine algae, the chlorarachniophyte algae), have retained it in the form of a nucleomorph: a small, compact remnant of the endosymbiont’s nucleus (Lane et al., 2006).
Morphology of Cryptomonads
Morphology of Cryptomonads
Cryptomonads are primarily unicellular (not in colonies), flagellates. Though cells are typically solitary and free-swimming, they do sometimes form amorphous mucilaginous colonies of non-motile/non-flagellated cells (this is called a "palmelloid state").
Cryptomonad cells have a flattened and asymmetric shape; they often look vaguely "slipper-shaped" in outline. At the front end of the cell is a depression called the vestibulum, which is shifted off to one side of the cell's midline (i.e., off-center), with the apex of the cell shifted off to the other side (hence, asymmetric). The vestibulum opens up into a longitudinal groove that extends towards the back end of the cell; this groove is often visible with the light microscope.
Crymptomonads have two flagella that are unequal in length (i.e., one is shorter than the other) and arise from the right margin of the vestibulum. As a result of the cell's asymmetry, cryptomonads rotate around their long axis as they swim (Clay, 2015).
Cryptomonad taxa vary with respect to the combinations of pigments they possess, and therefore exhibit a range of colors, including red, brown, and blue-green (Clay et al., 1999). Cryptomonas, a common representative genus, is brown to olive-brown in color.
(Above) Cryptomonad cells are often somewhat "slipper-shaped" in outline, as exemplified by the photos above.
(Above) Cryptomonads are typically solitary cells (not in colonies), but they do sometimes form loose colonies of cells surrounded by mucilage, as shown above.
(Above) Note the difference in length between the two flagella (one is shorter, one is longer). Also note how the point of insertion for the flagella is "off-center" (shifted off to one side of the midline of the cell).
Ecology of Cryptomonads
Ecology of Cryptomonads
While cryptomonads inhabit various types of waterbodies, their abundance and diversity is highest in the plankton of temperate lakes (Clay, 2015). Nine genera have been documented in freshwater habitats of North America (Wehr & Sheath, 2015), though Cryptomonas is likely the most abundant freshwater genus (Hoef-Emden & Archibald, 2017). Cryptomonas is regularly seen in water samples collected by NJCWST, and is the only representative genus we have thus far observed.
In addition to freshwater habitats, cryptomonads are also found in brackish and marine waters (Hoef-Emden & Archibald, 2017).
Genera Observed by NJCWST
Genera Observed by NJCWST
Cryptomonas
Image Gallery
Image Gallery
Click the arrows next to each genus listed below to view photos.
Cryptomonas
Blue-green crymptomonads (Chroomonas and/or Komma)
References
References
Clay, B. L., Kugrens, P., & Lee, R. E. (1999). A revised classification of the Cryptophyta. Botanical Journal of the Linnean Society, 131(2), 131–151.
Clay, B.L. (2015). Cryptomonads. In J. D. Wehr, R. G. Sheath, & J. P. Kociolek (Eds.), Freshwater Algae of North America: Ecology and Classification (2nd ed). Waltham, MA: Elsevier.
Hoef-Emden K. & Archibald J.M. (2017) Cryptophyta (Cryptomonads). In: Archibald J., Simpson A., Slamovits C. (eds) Handbook of the Protists. Springer, Cham. https://doi.org/10.1007/978-3-319-28149-0_35
Lane, C.E., Khan, H., MacKinnon, M., Fong, A., Theophilou, S., & Archibald, J.M. (2006). Insight into the diversity and evolution of the cryptomonad nucleomorph genome. Molecular Biology and Evolution, 23(5), 856–865. https://doi.org/10.1093/molbev/msj066
Wehr, J. D., & Sheath, R. G. (2015). Introduction to the Freshwater Algae. In J. D. Wehr, R. G. Sheath, & J. P. Kociolek (Eds.), Freshwater Algae of North America: Ecology and Classification (2nd ed). Waltham, MA: Elsevier.
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