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Phototrophs |
The euglenids (or euglenoids) are one of the best-known groups of flagellates, commonly found in freshwater especially when it is rich in organic materials, with a few marine and endosymbiotic members. Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex The excavates are a major assemblage of Protists often known as Excavata. The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a Johann Adam Otto Bütschli ( 3 May 1848, Frankfurt &ndash 2 February 1920, Heidelberg) was a German Zoologist The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a Flagellates are cells with one or more whip-like organelles called flagella. Many euglenids have chloroplasts and produce energy through photosynthesis, but others feed by phagocytosis or strictly by diffusion. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Phagocytosis is the cellular process of engulfing solid particles by the Cell membrane to form an internal Phagosome, or "food vacuole They belong to the phylum Euglenophyta, and their cell structure is typical of that group. The euglenids (or euglenoids) are one of the best-known groups of Flagellates commonly found in freshwater especially when it is rich in organic materials with a
Euglenids are distinguished mainly by the presence of a pellicle, which is composed of proteinaceous strips underneath the cell membrane, supported by dorsal and ventral microtubules. The pellicle is a thin layer supporting the Cell membrane in various Protozoa, protecting them and allowing them to retain their shape Microtubules are one of the components of the Cytoskeleton. They have a diameter of 25 nm and length varying from 200 nanometers to 25 micrometers This varies from rigid to flexible, and gives the cell its shape, often giving it distinctive striations. In many euglenids the strips can slide past one another, causing an inching motion called metaboly. Otherwise they move using the flagella.
The euglenids were first defined by Otto Bütschli in 1884 as the flagellate order Euglenida. Johann Adam Otto Bütschli ( 3 May 1848, Frankfurt &ndash 2 February 1920, Heidelberg) was a German Zoologist Botanists subsequently treated the algal division Euglenophyta; thus they were classified as both animals and plants, as they share characteristics with both. This conflict is an example of why the kingdom Protista was adopted. Protists (ˈproʊtɨst are a diverse group of eukaryotic Microorganisms Historically protists were treated as the kingdom Protista but this However, they retained their double-placement until the flagellates were split up, and both names are still used to refer to the group.
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Classification & Nutrition
The classification of euglenids is still variable, as groups are being revised to conform with their molecular phylogeny. To some extent, however, the results support the traditional groups based on differences in nutrition and number of flagella; at any rate these provide a starting point for considering euglenid diversity.
As with other Euglenozoa, the primitive mode of nutrition is phagocytosis. Phagocytosis is the cellular process of engulfing solid particles by the Cell membrane to form an internal Phagosome, or "food vacuole Prey such as bacteria and smaller flagellates are ingested through a cytostome, supported by microtubules. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have A cytostome or cell mouth is a part of a cell specialized for Phagocytosis, usually in the form of a Microtubule -supported funnel or groove These are often packed together to form two or more rods, which function in ingestion, and in Entosiphon form an extendable siphon. Most phagotrophic euglenids have two flagella, one leading and one trailing. The latter is used for gliding along the substrate. In some, such as Peranema, the leading flagellum is rigid and beats only at its tip.
Osmotrophic euglenids
In many cases exposure to certain chemicals or prolonged absence of light may kill off the chloroplasts without otherwise harming the organism. There are a number of species where chloroplasts are absent, formerly treated in separate genera such as Astasia (colourless Euglena) and Hyalophacus (colourless Phacus). Since they lack a developed cytostome, these forms feed exclusively by absorption.
References
External links
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