Diatoms and desmids are found in
Answers
For a molecule of two atoms, see Diatomic molecule.
Diatoms
Diatoms through the microscope.jpg
Light microscopy of a sampling of marine diatoms found living between crystals of annual sea ice in Antarctica; showing a multiplicity of sizes, shapes, and colors.
Scientific classification
Domain:
Eukaryota
(unranked):
SAR: a clade or supergroup that includes stramenopiles (heterokonts), alveolates, and Rhizaria.[1][2][3][4]
Superphylum:
Heterokonta
Phylum:
Ochrophyta
Class:
Bacillariophyceae
Dangeard, 1933[5]
Synonyms
Diatomea Dumortier, 1821[6]
Diatomophyceae Rabenhorst, 1864[7]
Bacillariae Haeckel, 1878[8]
Bacillariophyta Engler & Gilg, 1919[9]
Diatoms (diá-tom-os "cut in half", from diá, "through" or "apart"; and the root of tém-n-ō, "I cut".) [10] are a major group of algae[11] known as microalgae found in the oceans, waterways and soils of the world. Diatoms number in the trillions: they generate about 20 percent of the oxygen produced on the planet each year;[12] take in over 6.7 billion metric tons of silicon each year from the oceans in which they live;[13] and contribute nearly half of the organic material found in those oceans. The shells of dead diatoms can reach as much as a half mile deep on the ocean floor; and the entire Amazon basin is fertilized annually by 27 million tons of diatom shell dust transported by east-to-west (easterly) transatlantic winds from the Bodélé Depression, the bed of Lake Mega Chad in the Sahara[14] once covering much of the African Sahara.[15]
Diatoms are unicellular; they can live alone or form colonies, taking shapes such as ribbons, fans, zigzags, and stars. They range in size from 2 to 200 micrometers.[16] In the presence of adequate nutrients and sunlight, an assemblage of living diatoms doubles roughly every 24 hours by asexual reproduction; their life span, unless they are eaten, is about six days.[17] Diatoms have two shapes: a few (centric diatoms) are radially symmetric, while most (pennate diatoms) approach being bilaterally symmetric: this shape is the reason for the group name diatoms. A unique feature of diatom anatomy is that they are surrounded by a cell wall made of silica (hydrated silicon dioxide), called a frustule.[18] These frustules have structural coloration due to their photonic nanostructure, prompting them to be described as "jewels of the sea" and "living opals." Movement primarily occurs passively as a result of both water currents and wind-induced water turbulance; however, male gametes of centric diatoms have flagella, making them capable of active movement. Diatoms convert light energy to chemical energy by photosynthesis, an attribute they share with plants, although diatoms and plants evolved independently. Diatoms possess a urea cycle, a feature they share with animals, although it is used differently than in animals.
The study of diatoms is a branch of phycology. Diatoms are classified as eukaryotes, organisms with a membrane-bound cell nucleus, that separates them from the prokaryotes archaea and bacteria. Diatoms are a type of plankton called phytoplankton, the most common of the plankton types. Diatoms also grow attached to benthic substrates, floating debris, and on macrophytes. They compromise an integral component of the periphyton community.[19] Another classification divides plankton into eight types based on size: in this scheme, diatoms are classed as microalgae. Several systems for classifying the individual diatom species exist. Fossil evidence suggests that diatoms originated during or before the early Jurassic period, which was about 150 to 200 million years ago.
Diatoms are used to monitor past and present environmental conditions, and are commonly used in studies of water quality. Diatomaceous earth (diatomite) is a collection of diatom shells found in the earth's crust. They are soft, silica-containing sedimentary rocks which are easily crumbled into a fine powder, and typically have a particle size of 10 to 200 μm. Diatomaceous earth is used for a variety of purposes including for water filtration, as a mild abrasive, in cat litter, and as a dynamite stabilizer.
Answer
Chyrsophytes is the answer
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