Binucleid Rope Algae
Binucleid Rope Algae replaced their ancestor, developing sexual reproduction and spreading out globally to fill the largely empty colonial algae niches. They may form part of the base of many ecosystems, especially in freshwater. They form thick rope-shaped colonies, which have a hollow center. Unlike their ancestor, however, they are not only 1 cell thick—they may be 3-5 cells thick depending on the species, with the innermost layer being specialized for reproduction.
The reproduction of Binucleid Rope Algae begins in the innermost cell layer. Their dikaryotic reproductive cells will fuse their nuclei, temporarily becoming monokaryotic so that their chromosomes can cross over and exchange DNA. Afterwards, the nucleus splits into four genetically distinct nuclei, followed by the cell itself also splitting in four—creating four distinct mononucleic spore cells. These are then released from the ends of the rope, and they will go on to fuse with spore cells of other Binucleid Rope Algae and form new colonies. Binucleid Rope Algae can also reproduce by fragmentation, as a rope that is too long will break apart and its cells will grow into new ropes.
Binucleid Rope Algae can be found anywhere where there is water and sunlight, from the open ocean to rocky coastlines to rivers, lakes, and wetlands. They are also capable of growing on land, usually attached to rocks or flora, via water sources such as snow and the ever-wet nature of rainforests. Some species float on or near the surface of water, while others attach to rocks, flora, sediment, and even shelled fauna. Most species have some method of going dormant, which allows individual cells to survive extended periods of time in sunless ground water or during long polar nights. Distinguishing species can be difficult, especially from cells alone, and some species form different shapes such as spirals to maximize space efficiency and photosynthesis.