| Sorastrum | |
|---|---|
|   | |
| Sorastrum spinulosum | |
| Scientific classification   | |
| Kingdom: | Plantae | 
| Division: | Chlorophyta | 
| Class: | Chlorophyceae | 
| Order: | Sphaeropleales | 
| Family: | Hydrodictyaceae | 
| Genus: | Sorastrum Kützing | 
| Type species | |
| Sorastrum echinatum (Meneghini) Kützing [1]  | |
| Species | |
Sorastrum is a genus of green algae in the family Hydrodictyaceae. [2] It is a component of the phytoplankton of freshwater ponds, lakes, and ditches. Sorastrum is common in tropical to temperate regions of the world, [1] but due to its small size it is often overlooked. [3]
The genus was named by Friedrich Traugott Kützing and comes from the Ancient Greek terms σωρός (sōrós, "heap") and ἄστρον (astron, "star"). [4]
Sorastrum forms spherical colonies of 8 to 128 cells. [5] Individual cells are kidney-shaped, pear-shaped, or wedge-shaped, or spherical (in Sorastrum sphericum ) [3] and attached to a central body of mucilage via gelatinous strands. On each cell there are two to four outwardly pointing spines. Each cell contains a single chloroplast with a one pyrenoid. [6]
Identification of species depends on the size and shape of the cells, particularly the spines. [1]
Reproduction occurs asexually, by zoospores. Zoospores have two flagella each and are formed by the repeated division of the protoplast. Once divided, the zoospores are released from a tear in the mother cell wall. Sexual reproduction has not been observed in Sorastrum, but is presumed to be similar to that of Hydrodictyon and Pediastrum . [1]