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Euglena is a genus of single cell flagellate eukaryotes. It is the best known and most widely studied member of the class Euglenoidea, a diverse group containing some 54 genera and at least 200 species. [1] [2] Species of Euglena are found in fresh water and salt water.
The red eyespot of a euglena filters light for the photoreceptor so that only certain wavelengths of light are able to reach the photoreceptor, allowing the euglena to “steer” itself by moving toward light in different intensities in different areas of its photoreceptor. Key: 1. Microtubules that make up the pellicle (see 9.) 2.
Euglena gracilis is a freshwater species of single-celled alga in the genus Euglena. It has secondary chloroplasts, and is a mixotroph able to feed by photosynthesis or phagocytosis. It has a highly flexible cell surface, allowing it to change shape from a thin cell up to 100 μm long to a sphere of approximately 20 μm.
These arise from a basal body. In some flagellates, flagella direct food into a cytostome or mouth, where food is ingested. Flagella role in classifying eukaryotes. Among protoctists and microscopic animals, a flagellate is an organism with one or more flagella.
Later, various biologists described additional characteristics for Euglena and established different classification systems for euglenids based on nutrition modes, the presence and number of flagella, and the degree of metaboly.
The genus was established in 1841 and since then major discoveries have led it to become an extremely large group containing hundreds of species with varied physiological characteristics. Contemporary studies agree that Phacus is not monophyletic or holophyletic, but is actually polyphyletic .
Peranema. Peranema's basic anatomy is that of a typical euglenid.The cell is spindle or cigar-shaped, somewhat pointed at the anterior end. It has a pellicle with parallel finely-ridged proteinaceous strips underlain by microtubules arranged in a helical fashion around the body.
Euglenales consists mostly of freshwater organisms, in contrast to its sister Eutreptiales which is generally marine. Cells have two flagella, but only one is emergent; the other is very short and does not emerge from the cell, so cells appear to have only one flagellum. [3]