Euglenozoa | |
---|---|
Two Euglena | |
Scientific classification | |
Domain: | Eukaryota |
Superphylum: | Discicristata |
Phylum: | Euglenozoa Cavalier-Smith, 1981[2] |
Classes | |
|
The Euglenozoa are a large phylum of flagellate protists. They are part of the wastebasket taxon known as the Protozoa, which had many obviously different protists.
Euglenozoa include a variety of common free-living species, and some important parasites, of which a few infect humans. There are two main subgroups, the Euglenoidea "euglenids" and Kinetoplastea "kinetoplastids".[3] Euglenozoa are unicellular, mostly around 15–40 µm in size, although some euglenids get up to 500 µm long.
Most Euglenozoa have two flagella, parallel to one another in a pocket-like structure. In some there is a cytostome or mouth, used to eat bacteria or other small organisms. This is supported by a microtubule from the flagellar bases; two other tubules support the dorsal and ventral surfaces of the cell.[4]
Some other Euglenozoa feed through absorption, and many euglenids have chloroplasts and so get energy by photosynthesis. These chloroplasts are surrounded by three membranes and contain chlorophylls A and C, and other pigments,[3] so are probably evolved from those of a captured green alga. Reproduction occurs only by cell division. During mitosis, the nuclear membrane remains intact, and the spindle microtubules form inside it.[4]
The group is characterized by the ultrastructure of the flagella. In addition to the normal supporting microtubules, each contains a rod (called paraxonemal), which has a tubular structure in one flagellum and a latticed structure in the other.[5]
The euglenozoa are generally accepted as monophyletic. They are related to Percolozoa. The two share mitochondria with disk-shaped compartments, which only occurs in a few other groups.[6] Both probably belong to a larger group of eukaryotes called the Excavata.[7] This grouping has been challenged.[8]
((cite journal))
: CS1 maint: numeric names: authors list (link)
((cite journal))
: CS1 maint: numeric names: authors list (link)
((cite journal))
: CS1 maint: numeric names: authors list (link)
((cite journal))
: CS1 maint: numeric names: authors list (link)
((cite journal))
: CS1 maint: numeric names: authors list (link)