Diatom
Diatoms are a type of algae (tiny plant-like living things often found in water). Most are single cells, but some form chains or simple colonies. They usually live in the ocean, but are also found in some soils and waterways.
| Diatoms | |
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| Marine diatoms | |
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| Class: | Bacillariophyceae
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Characteristics
Cell walls
Diatom cells have unique cell walls made of silica (SiO2). These walls (called "frustules") take many forms, some quite beautiful and ornate.
The name "diatom" comes from the ancient Greek word diátomos, which means 'cut through.' Diatom cell walls are usually split (or 'cut through') into two sides.
Function
Living diatoms comprise about 20 to 50 percent of the oxygen produced annually.[1][2] They take in over 6.7 billion metric tons of silicon each year from the waters in which they live.[3]
Similar organisms
Diatoms and coccoliths are the two great groups of single-celled organisms in the sea. They do not grow in the same places, because diatoms are silica and coccoliths are made of calcium carbonate. T.H. Huxley first discovered this on his voyage on HMS Rattlesnake in 1846–1850.
Evolution
Archeologists have found diatom fossils from as far back as the Lower Jurassic period, around 185 million years ago. However, molecular clock evidence suggests that they developed even earlier.[4]
Scientists have analyzed the entire genomes of two diatom species. The analysis revealed both species had hundreds of genes that came from bacteria.[5]
Diatoms probably evolved some of their structure from red algae.
Uses
Diatoms have some practical uses. Scientists can study it to determine water quality, monitor environmental conditions like pollution, and understand what past environments were like.
Diatom communities are also of interest to nanotechnology.
Diatom Media
Selections from Ernst Haeckel's 1904 Kunstformen der Natur (Art Forms of Nature), showing pennate (left) and centric (right) frustules.
Shape classification of diatom frustules. The images are 3D models. The actual sizes of the frustules are about 10–80 μm. 
Structure of a centric diatom frustule 
Pennate diatom from an Arctic meltpond, infected with two chytrid-like [zoo-]sporangium fungal pathogens (in false-colour red). Scale bar = 10 μm.
Light microscopy of a living diatom. Numbered graduations are 10 micrometres apart
Assorted diatoms (unknown species) isolated from moss in Bangalore, India.
References
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Wikispecies has information on: Diatom. |
- ↑ "The air you're breathing? A diatom made that". Live Science. 11 June 2014. Archived from the original on 30 April 2018. Retrieved 30 April 2018.
- ↑ "What are diatoms?". Diatoms of North America. Archived from the original on 25 January 2020. Retrieved 28 January 2020.
- ↑ Treguer, P.; Nelson, D.M.; Van Bennekom, A.J.; Demaster, D.J.; Leynaert, A.; Queguiner, B. (1995). "The silica balance in the world ocean: a reestimate". Science. 268 (5209): 375–9. Bibcode:1995Sci...268..375T. doi:10.1126/science.268.5209.375. PMID 17746543. S2CID 5672525.
- ↑ Kooistra W.H.C.F. and Medlin L.K. 1996. Evolution of the diatoms (Bacillariophyta): IV. A reconstruction of their age from small subunit rRNA coding regions and the fossil record. Mol. Phylogenet. Evol. 6, 391-407.
- ↑ Bowler C. et al. 2008. The Phaeodactylum genome reveals the evolutionary history of diatom genomes. Nature 456: 239–244.