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| genus_authority = [[Christian Gottfried Ehrenberg|Ehrenberg]], 1830
| genus_authority = [[Christian Gottfried Ehrenberg|Ehrenberg]], 1830
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'''''Euglenas''''' (singular, Euglena) are common [[protists]], of the class [[euglenoids]] of the [[phylum]] [[Euglenophyta]], and of the [[Domain]] [[Eukaryota]].
'''''Euglenas''''' (singular, Euglena) are common [[protist]]s, typical of the [[euglenoid]]s (also [[euglenids]]), and commonly found in nutrient-rich freshwater, with a few marine species. It is considered a [[flagellate]]. The cells vary in length from around 20 to 300 [[μm]], and are typically cylindrical, oval, or spindle-shaped with a single emergent [[flagellum]] for movement. There are usually many bright green [[chloroplast]]s, If sunlight is not available, it can absorb nutrients from decayed organic material. Euglena is also found in sewage systems. Euglena have a [[contractile vacuole]] which maintains the concentration of water and salts within the cell by expelling excess water. The name comes from the [[Greek language|Greek]] words ''{{polytonic|εὔ}} (eu)'' and ''{{polytonic|γλήνη}} (glēnē)'', meaning ''good eyeball'', referring to Euglena's stigma (also known as [[Eyespot apparatus|eyespot]]).
⚫
1000 species of ''Euglena'' have been described. Marin ''et al.'' (2003) revised the genus so that it forms a [[monophyletic]] group, moving several species with rigid pellicles to the genus ''Lepocinclis'' and including several species without chloroplasts, formerly classified as ''Astasia'' and ''Khawkinea''.
Until the discovery of the paraflagellar body it was wrongly believed that this was the organelle responsible for the sensing of light. Instead it is just a small part of Euglena's [[Eyespot apparatus|light receptive system]] and its role is to shield light from the actual light sensitive paraflagellar body (PFB) or so-called photoreceptor.
Orientation of the organism towards light is called [[Phototaxis]].


===Characteristics===
⚫
Over 1000 species of ''Euglena'' have been described. Marin ''et al.'' (2003) revised the genus so that it forms a [[monophyletic]] group, moving several species with rigid pellicles to the genus ''Lepocinclis'' and including several species without chloroplasts, formerly classified as ''Astasia'' and ''Khawkinea''.
Commonly found in nutrient-rich freshwater, although there are a few marine species.
Considered to be a [[flagellate]]
The cells vary in length from around 20 to 300 [[μm]].
Cell shape is typically cylindrical, oval, or spindle-shaped with a single emergent [[flagellum]] for movement.
Often contains many green [[chloroplast]]s, to generate nutrients by means of [[photosynthesis]] However, if sunlight is not available, it can also absorb nutrients from decayed organic material. Euglena have a [[contractile vacuole]] which maintains the concentration of water and salts within the cell by expelling excess water.
Euglena also contains an [[Eyespot apparatus|light receptive system]] The sole role of the Eyespot apparatus is to shield light from the very light sensitive paraflagellar body (PFB) or so-called [[photoreceptor]] which is beneath the Eyespot Apparatus. Until the discovery of the paraflagellar body it was wrongly believed that this was the organelle responsible for the sensing of light.

===Etymology===
The name comes from the [[Greek language|Greek]] words ''{{polytonic|εὔ}} (eu)'' and ''{{polytonic|γλήνη}} (glēnē)'', meaning ''good eyeball'', referring to Euglena's stigma (also known as [[Eyespot apparatus|eyespot]]).


==See also==


==References==
==References==

Revision as of 02:01, 15 February 2008

Euglenoids (Euglenids)
Scientific classification
Domain:
Eukaryota
Kingdom:
Protista
(unranked):
Excavata
Phylum:
Euglenozoa
Class:
Euglenoidea
Order:
Euglenales
Family:
Euglenaceae
Genus:
Euglena

Ehrenberg, 1830

Euglenas (singular, Euglena) are common protists, of the class euglenoids of the phylum Euglenophyta, and of the Domain Eukaryota. Currently, over 1000 species of Euglena have been described. Marin et al. (2003) revised the genus so that it forms a monophyletic group, moving several species with rigid pellicles to the genus Lepocinclis and including several species without chloroplasts, formerly classified as Astasia and Khawkinea.


Characteristics

Commonly found in nutrient-rich freshwater, although there are a few marine species. Considered to be a flagellate The cells vary in length from around 20 to 300 μm. Cell shape is typically cylindrical, oval, or spindle-shaped with a single emergent flagellum for movement. Often contains many green chloroplasts, to generate nutrients by means of photosynthesis However, if sunlight is not available, it can also absorb nutrients from decayed organic material. Euglena have a contractile vacuole which maintains the concentration of water and salts within the cell by expelling excess water. Euglena also contains an light receptive system The sole role of the Eyespot apparatus is to shield light from the very light sensitive paraflagellar body (PFB) or so-called photoreceptor which is beneath the Eyespot Apparatus. Until the discovery of the paraflagellar body it was wrongly believed that this was the organelle responsible for the sensing of light.

Etymology

The name comes from the Greek words εὔ (eu) and γλήνη (glēnē), meaning good eyeball, referring to Euglena's stigma (also known as eyespot).


References

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