Sphaeroplea
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| Sphaeroplea | |
|---|---|
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| Sphaeroplea annulina | |
Scientific classification  | |
| Kingdom: | Plantae |
| Division: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Sphaeropleales |
| Family: | Sphaeropleaceae |
| Genus: | Sphaeroplea C.Agardh |
| Species | |
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See text | |
Sphaeroplea is a genus of green algae in the family Sphaeropleaceae.[1] It was first circumscribed by the Swedish botanist Carl Adolph Agardh in 1824.[2]
Sphaeroplea consists of unbranched filaments of cells, one cell thick. Cells are usually 10–50 μm in diameter, but one variety can reach up to 170 μm in diameter. Cells are cylindrical, several times longer than wide, with a linear series of alternating vacuoles and cytoplasmic zones containing nuclei and chloroplasts. The chloroplasts are band-shaped, and contain several pyrenoids. Nuclei are typically in pairs.[2][3]
Reproduction
Sphaeroplea reproduces asexually and sexually. In asexual reproduction, the filaments break apart, although one species has been observed to produce zoospores that are biflagellate (i.e. with two flagella).[4] Sexual reproduction is typically oogamous, where vegetative cells become reproductive cells without changing their shape.[3] Female gametes are large, spherical and green, and are borne in one to several rows within the cell. Male gametes are typically produced on the same filament as female gametes, and are small and biflagellate.[2]
After the gametes fuse, a zygote (termed an oospore) is formed. Zygotes develop a thick cell wall with ornamentation, and eventually turn reddish-orange before being released. The zygotes may last for an extended period of time in a desiccated state. During germination, the zygote becomes four biflagellate cells that attach to a substrate, lose their flagella, and develop into a new filament.[2]
