Euglenophyceae (

ICNafp The ''International Code of Nomenclature for algae, fungi, and plants'' (ICN or ICNafp) is the set of rules and recommendations dealing with the formal botanical names that are given to plants, fungi and a few other groups of organisms, all th ...

, proposed as a

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

) or Euglenea ( ICZN, proposed as a class) is an unranked

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

of single-celled

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

belonging to the phylum Euglenozoa. They have

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s originated from an event of secondary endosymbiosis with a

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

. They are distinguished from other algae by the presence of paramylon as a storage product and three membranes surrounding each chloroplast.

Description

Euglenophyceae are

unicellular A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic organisms and ...

protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists do not form a natural group, or clade, but are a paraphyletic grouping of all descendants of the last eukaryotic common ancest ...

s that contain

s. Their chloroplasts originated from a secondary endosymbiosis with a

, particularly from the order Pyramimonadales, and contain chlorophylls ''a'' and ''b''.Some have secondarily lost this ability and evolved toward osmotrophy. In addition to photosynthetic plastids, most species have a photosensitive eyespot.

Ecology

Euglenophyceae are mainly present in the water column of freshwater habitats. They are abundant in small eutrophic water bodies of

temperate climate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...

s, where they are capable of forming blooms, including toxic blooms such as those caused by '' Euglena sanguinea''. In

tropical climate Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. Tropical climates are defined by a monthly average temperature of or higher in the coolest month, featuring hot te ...

, blooms are common in ponds. In marine environments they have been reported in a lower amount. Some species are capable of migrating vertically through the sand along with the cycles of ocean tides. Two lineages of Euglenophyceae are part of the marine plankton: Rapazida and Eutreptiales. Eutreptiales can amount up to 46% of the total phytoplankton biomass when blooming in eutrophic coastal waters.

Classification

Euglenophyceae encompasses three taxonomic groups: the mixotrophic '' Rapaza viridis'' and two mainly phototrophic orders, Euglenales and Eutreptiales. The classification is as follows (

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

numbers based on

AlgaeBase AlgaeBase is a global species database of information on all groups of algae, both seaweed, marine and freshwater algae, freshwater, as well as sea-grass. History AlgaeBase began in March 1996, founded by Michael D. Guiry, Michael Guiry. Text ...

): * Order Euglenales ** Family Euglenaceae uglenidae *** '' Colacium'' – 17 spp. *** '' Cryptoglena'' – 11 spp. *** ''

Euglena ''Euglena'' is a genus of Unicellular organism, single-celled, 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. Species of '' ...

'' – 174 spp. *** '' Euglenaformis'' – 3 spp. *** '' Euglenaria'' – 4 spp. *** '' Monomorphina'' – 17 spp. *** '' Strombomonas'' – 99 spp. *** '' Trachelomonas'' – 410 spp. ** Family Phacaceae hacidae *** '' Discoplastis'' – 6 spp. *** '' Flexiglena'' – 1 sp. *** '' Lepocinclis'' – 90 spp. *** '' Phacus'' – 188 spp. * Order Eutreptiales ** Family Eutreptiaceae utreptiidae *** '' Eutreptia'' – 11 spp. *** '' Eutreptiella'' – 9 spp. * Order Rapazida ** Family Rapazidae *** '' Rapaza'' – 1 sp. Several genera assigned to Euglenophyceae are considered ''

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'', because the lack of genetic data makes their

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

position unresolved: * '' Ascoglena'' – 4 spp. * '' Euglenamorpha'' – 2 spp. * '' Euglenopsis'' – 11 spp. * '' Glenoclosterium'' – 1 sp. * '' Hegneria'' – 1 sp. * '' Klebsina'' – 1 sp. * '' Euglenocapsa'' – 1 sp. * '' Menoidium'' – 28 spp. * '' Parmidium'' – 10 spp.

References

{{taxonbar, from=Q2356588 Euglenozoa classes Algae Taxa described in 1925 Euglenozoa