Diatom
Description
Diatoms are tiny, single-celled algal plants that are made of silica and other minerals. They are typically found in marine environments, but can survive in other areas with enough moisture, including soil habitats. Each of the more than 8,000 species has a skeleton that is ornate and symmetrical, unique from that of every other species. The skeletons can take the shape of crescents, discs, rectangles, triangles, stars, or other different geometric shapes. One of its byproducts, called diatomaceous earth, has various practical applications due to its silica content and extremely small size [2].
Taxonomy
While diatoms belong to the supergroup chromalveolates, individual species can be incredibly difficult to identify due to their sheer numbers as well as inconsistency in how observations are interpreted. This results in multiple taxa being lumped together for ease of comparison. Even with 75,000 taxa already recognized, many regions of the earth have neither been explored for their presence or absence nor inventoried if they do exist. As a result of these conundrums, the identification of taxa depends on the precise observation of discrete and continuous features, primarily those seen in the diatoms' glassy cell walls. Many classification guides have been developed through the years with the goal of creating a standard with more clear categories and organization [3].
| Domain: | Eukaryota |
|---|---|
| Kingdom: | Plantae |
| Clade: | Diaphoretickes |
| Phylum: | Gyrista |
| Subphylum: | Ochrophytina |
| Superclass: | Khakista |
| Class: | Bacillariophyceae |
| [4] | |
Ecology
The lack of data on the ecology of terrestrial diatoms is the greatest barrier to future research. Terrestrial diatoms can be used as indicators for the quality of both aquatic and soil environments. Also, land use and soil pH are important factors in determining the ecological condition of the diatom sites and have the greatest influence on how their communities are structured. Studies looking at soil algae populations as a whole have revealed that they are very sensitive to disturbance causes [5]. In a range of terrestrial environments, including soils, mosses, wet walls, and rocks, many taxa may persist and reproduce. For diatoms, forests provide a stable microhabitat, and agricultural techniques, rather than seasonal variations in environmental factors, regulate the majority of the diatom communities' temporal fluctuation. Lastly, diatoms play a very crucial role in the carbon cycle by facilitating the production of chemical energy in organic compounds [6].
Anatomy
Diatoms also have the ability to generate a porous silica cell wall, known as the frustule, that makes up the structure of their skeleton. These cell walls display a staggering variety of pore patterns and species-specific forms. They typically belong to one of two anatomical categories-centrales or pennates—characterized by either radial or bilateral symmetry of their frustule, respectively. In both situations, the live cell is enclosed by a hypotheca that is inserted into a somewhat larger epitheca inside the frustule. The frustule's size varies from a few microns to millimeters depending on the species. The hypotheca and epitheca can both be thought of as valves encircled by lateral girdles. Each layer of a valve is composed of a number of pores in more or less regular patterns, the size and location of which vary depending on the species and layer [8]. Their form and function are also made up of other morphological characteristics such as pore size, shape, porosity, and pore organization. For example, pore size and organization can be optimized to be smaller, which allows for more efficient blocking of viruses or other harmful particles [9]. Diatoms are so complex, there are even more structures and characteristics worth mentioning. A number of silica bands are connected by their borders to form the girdle, which connects the protoplasm with the frustule. The first girdle bands can be one of the factors in determining the overall shape and ability of the diatom. Research on their nanostructures will continue for quite some time, especially for engineering we can apply on a larger scale [10].
References
[1] "Mixed diatom frustules" by Carolina Biological Supply Company is licensed under CC BY-NC-ND 2.0
[2] Calvert, R. (December 1930). "Diatomaceous earth". Journal of Chemical Education, 7(12), 2829. https://doi.org/10.1021/ed007p2829
[3] Blanco, S. (May 2020). "Diatom taxonomy and Identification Keys. Modern Trends in Diatom Identification". Developments in Applied Phycology, vol 10. Springer, Cham. 25–38. https://doi.org/10.1007/978-3-030-39212-3_3
[4] Retrieved May 6, 2023, from the Integrated Taxonomic Information System (ITIS) on-line database, www.itis.gov, CC0 https://doi.org/10.5066/F7KH0KBK
[5] Antonelli, M., C. E. Wetzel, L. Ector, A. J. Teuling, & L. Pfister. (April 2017). "On the potential for terrestrial diatom communities and diatom indices to identify anthropic disturbance in soils" Ecological Indicators 75:73–81. https://doi.org/10.1016/j.ecolind.2016.12.003
[6] Foets, J., C. E. Wetzel, A. J. Teuling, & L. Pfister. (January 2020). "Temporal and spatial variability of terrestrial diatoms at the catchment scale: Controls on communities". PeerJ 8. https://doi.org/10.7717/peerj.8296
[7] "Ocean carbon cycle and diatom carbon dioxide concentration mechanisms 2" by Juan José Pierella Karlusich, Chris Bowler, and Haimanti Biswas is licensed under CC BY-SA 4.0
[8] De Tommasi, E., J. Gielis, & A. Rogato. (July 2017). "Diatom frustule morphogenesis and Function: A multidisciplinary survey". Marine Genomics 35:1–18. https://doi.org/10.1016/j.margen.2017.07.001
[9] Losic, D., G. Rosengarten, J. G. Mitchell, & N. H. Voelcker. (April 2006). "Pore architecture of diatom frustules: Potential nanostructured membranes for molecular and particle separations". Journal of Nanoscience and Nanotechnology 6:982–989. https://doi.org/10.1166/jnn.2006.174
[10] De Stefano, M. & L. De Stefano. (January 2005). "Nanostructures in diatom frustules: Functional morphology of valvocopulae in Cocconeidacean monoraphid taxa". Journal of Nanoscience and Nanotechnology 5:15–24. https://doi.org/10.1166/jnn.2005.001
[11] "Longitudinal Diatom (Labelled)" by Esseh~commonswiki is licensed under CC BY-SA 3.0
