Classes of Algae

Algae refers to a wide variety of single and multicellular organisms that range in size from microscopic phytoplankton to giant marine kelp. Algal blooms are usually attributable to large quantities of nitrogen and phosphorus in aquatic systems. Common characteristics among algae include chlorophyll pigment, storage molecules and motility structures. Several classes of algae exist, but the most common types are more abundant within the ecosystem.

  1. Euglenoids

    • Euglenoids are found in both parasitic and free-living form. The majority of the eukaryotes are colorless and without chloroplasts -- characteristics that are atypical for algae. Euglenoids acquire chloroplasts through endosymbiosis with green algae.The majority of organisms possess flagella, or "complex projections that last back and forth to propel the organism from place to place," according to Kenyon College. They live in a variety of ecosystems, ranging from bloodstreams of host organisms to freshwater streams.

    Golden Algae

    • Chrysophytes, or golden algae, exist as microscopic organisms in fresh water. The vast majority of the species is photosynthetic. They serve as the primary source of food for zooplankton in their habitat. Golden algae species are mostly free-swimming and unicellular, but some exist in colonies. The species Synurophyceae "produce siliceous covering that may have bristles or scales with quite complex structures." Golden algae have a fairly complete fossil record because the group secretes silica that is abundant in rock deposits.

    Green Algae

    • Green algae, which is separated into 7,000 species, is the most diverse algae group. It contains two forms of chlorophyll similarly to plants. Green algae capture light energy to fuel the manufacture of sugars through the process of photosynthesis. They are aquatic, unlike most plants. Green algae absorb nitrogen through animal waste and provide oxygen for aquatic animals in return. Green algae are immobile. They remain within a colony and float along the water's currents.

    Anabaena

    • Anabaena is a group of filamentous nitrogen-fixing cyanobacteria that is often grouped with algae. It is informally known as blue-green algae, although it is not a member of the species. Anabaena is microscopic in size with no organized nucleus. The species has straight or curved trichoms that form the cell walls. The blue or yellow-green cells grow in filamentous clumps that resemble a string of beads. Anabaena are often found living in specialized chambers within ferns. The symbiotic relationship benefits the fern, which "gains a usable source of organic nitrogen," according to Western New Mexico University.