[1][2] Species within this genus are found in both marine and freshwater ecosystems across the globe; their habitat range is mainly limited by water depth due to their photosynthetic nature.

[1] Thus, they live in diverse water environments if enough nutrients and light are available for net photosynthetic activity.

[5] The genus Tetraselmis has undergone many taxonomic changes over the years, largely due to more advanced research techniques that have aided scientists in their classification.

Tetraselmis species are found in both marine and freshwater ecosystems, and they occupy niches as primary producers in benthic and planktonic food webs.

Planktonic photoautotrophs are important components of aquatic food webs because they form the first trophic level.

[1] Marine species often populate rapidly and densely, causing plankton blooms in shoreline and bay areas.

Cells can be round, ovoid, elliptical, flattened, compressed, or a combination of these shapes, in which their side lengths can vary in range from 3.5-25 μm.

[1] Generally, individual cells travel in a linear fashion for a long period of time, and then rapidly change direction without stopping, in which their flagella generate force for motion through an aqueous environment.

[1] Stigmas are a concentration of pigment granules which the cell uses to detect light allowing them to orientate themselves within the water column.

[1] The pore is a long slit with thecal extensions that border it, extending upwards to protect the flagella base.

[1] The flagella emerge from the apical depression in pairs and point in opposite directions, running parallel to the long side of the cell.

[1] They are also covered in flagellar hairs which are loosely attached to the cell exterior; they are cross-striated with two scale layers on flagella.

The flagellar hairs have a distinct sequence of structural components, the proximal filament connects the flagellum and cell surface, this is followed by the tubular shaft, then the transition zone in which the shaft is modified, followed by a stretch of linear globular subunits, and the hair ends with a distal filament.

[1] Cells in the cyst stage lose their flagella, and are termed as being aflagellate, and they produce a thick thecal-shell for protection.

[1] Additionally, vegetative cells whether flagellate or immotile are anchored to the thecal wall by four microtubule contact points.

[1] Tetraselmis species have been important for cellular biology research, for studying plankton growth cycles, and they may have future use in biofuel production.

[3] Scientists believe this phenomenon allows clones to form “sub-populations” that remain close to one another, in which the cells cooperate with one another and act as one large population.

[4] Tetraselmis species, along with other microalgae are a promising source for biofuel use due to their fast growth rate, high lipid content, cheaper photosynthetic mechanisms, less need for agricultural land, useful by-products, and for being environmentally friendly.

[citation needed] T. suecica exopolysaccharides have antioxidant activity and cytotoxic effects on tumor cells; therefore, they could offer greater advantages as possible natural nutraceuticals for the pharmaceutical industry.