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Golden algae

life science Maturity 11-13 Next article →

Golden algae, scientifically known as Chrysophyceae, are a diverse group of microorganisms found primarily in freshwater environments. They are also frequently called chrysophytes, chrysomonads, or golden-brown algae. These organisms play a vital role in aquatic ecosystems by helping scientists study food web dynamics. They are particularly useful for assessing environmental degradation caused by factors like acid rain or eutrophication.

Ochromonas
Ochromonas

The movement of many golden algae is driven by specialized structures called flagella. In a typical motile cell, there are two distinct flagella that work together to navigate the water. One is an active, "feathered" flagellum that features tiny hairs known as mastigonemes. This feathered structure is oriented toward the direction of travel to pull or push the cell forward. The second flagellum is usually smooth and acts as a passive stabilizer. While some species like Chromulina appear to have only one flagellum, structural studies show a second basal body is always present.

Album général des Cryptogames, Pl. 2
Album général des Cryptogames, Pl. 2

Beyond swimming, golden algae exhibit a wide variety of physical forms and lifestyles. Most members are unicellular flagellates, but some live in complex structures. For example, the genus Dinobryon grows in branched colonies and uses a shell called a lorica. Other species, such as Chrysamoeba, exhibit amoeboid behavior by using long, branching cell extensions to move. Some even undergo a complex life cycle involving a multinucleate plasmodial stage, which is similar to the life cycle of slime molds.

Hikarimohitachi
Hikarimohitachi

A defining characteristic used to identify Chrysophyceae is the production of a siliceous cyst. This hard, glass-like structure is formed inside the cell and is known by names like statospore, stomatocyst, or statocyst. These cysts are typically globose, or round, and feature a single pore. The surfaces of these mature cysts can be decorated with intricate ornamental patterns. Because these patterns vary between species, scientists use them as essential tools for classification.

Fucoxanthin
Fucoxanthin

The history of classifying these algae has changed significantly as technology has improved. In 1910, a researcher named Pascher defined the order Chromulinales. Over the decades, many scientists provided different organizational systems. Smith proposed a classification in 1938 involving several suborders like Cromulinae and Isochrysidineae. Bourrely offered a different view in 1957, and later researchers like Kristiansen and van den Hoek updated these groupings. Today, they are often placed within a larger group called the Stramenopiles, which includes various non-algae like bicosoecids and oomycete fungi.

Evolutionary biology provides a fascinating look at how golden algae acquired their unique traits. They contain a pigment called fucoxanthin, which gives them their golden color and aids in photosynthesis. Because of this pigment, they were once thought to be a specialized form of cyanobacteria. However, the fossil record tells a different story. Because many chrysophytes produce silica capsules, they leave behind excellent fossils. These fossils show that their ancestors were likely heterotrophic flagellates that could not photosynthesize.

Modern science suggests that these algae developed photosynthesis through an endosymbiotic relationship. This means their ancestors likely took in cyanobacteria that already contained fucoxanthin. This partnership allowed the golden algae to transition from being hunters to being able to use light for energy. This evolutionary leap allowed them to thrive in various freshwater niches. By studying these complex histories, biologists continue to refine our understanding of the entire Stramenopile lineage.

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🖼️ Images & Media (4)
File:Ochromonas.png
Ochromonas.png
File:Album général des Cryptogames, Pl. 2.jpg
Album général des Cryptogames, Pl. 2.jpg
File:Hikarimohitachi.jpg
Hikarimohitachi.jpg
File:Fucoxanthin.svg
Fucoxanthin.svg
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