Euglenids
| Euglenids Temporal range: Eocene (53.5Ma) - recent |
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| Scientific classification | |
| Domain: | Eukaryota |
| (unranked): | Excavata |
| Phylum: | Euglenophyta |
| Class: |
Euglenophyceae Schoenichen, 1925 |
| Major groups | |
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Phototrophs |
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| Synonyms | |
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Phototrophs
Euglenales
Eutreptiales
Osmotrophs
Rhabdomonadales
Phagotrophs
?Heteronematales
?Sphenomonadales
Euglenids (euglenoids, or euglenophytes, formally Euglenida, ICZN, or Euglenophyceae, ICBN) are one of the best-known groups of flagellates, which are Excavate Eukaryotes of the phylum Euglenophyta and their cell structure is typical of that group. They are commonly found in freshwater, especially when it is rich in organic materials, with a few marine, and endosymbiotic members. Most euglenids are unicellular. Many euglenids have chloroplasts and produce their own food through photosynthesis, but others feed by phagocytosis, or strictly by diffusion. This group is known to contain carbohydrate paramylon.
Euglenoids are said to descend from an ancestor that took up green algae by secondary endosymbiosis.
Euglenoids are distinguished mainly by the presence of a pellicle (periplast), which is composed of proteinaceous strips underneath the cell membrane, supported by dorsal and ventral microtubules. 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 euglenoids were first defined by Otto Bütschli in 1884 as the flagellate order Euglenida, as an animal. Botanists subsequently created 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. However, they retained their double-placement until the flagellates were split up, and both names are still used to refer to the group. Their chlorophyll are not masked with accessory pigments.
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Wikipedia