Hair Nimbuses

Hair Nimbuses split from their ancestor. This genus of nimbus forms long colonial chains which are less susceptible to becoming saturated with water and falling. This is due to their high association with real clouds, aided by the appearance of Cloudbubbles which can serve as structural support. Clouds are the wettest part of the atmosphere—basically an oasis in a habitat otherwise more arid than a desert—and to take advantage of this water source, avoiding too much saturation is necessary to their survival. In addition to the sky, they are also present in montane regions, cloud forests, and anywhere else where fog or ground-level cloud cover is common, but in these habitats they are tethered to rocks and rooted flora. They may also occasionally grow on hibernating fauna. They stand out from other nimbuses in that, in three dimensions, they actually resemble the two-dimensional representations, only having fronds growing in a ring around the main body of the cell.

In order to keep their genome fresh, Hair Nimbus cells are capable of mating. Like in many unicellular eukaryotes on Earth, they do so by fusing and then undergoing meiosis. However, their many fronds and status as aeroplankton make this a difficult endeavor, as their chances of meeting outside of colonies and coming close enough to actually mate are very low. They mitigate this by mating when colonies collide: the filamentous shape of the colony causes them to become tangled easily anyway, and they come apart during the process of meiosis, so they both undergo sexual reproduction and avoid becoming vulnerable to saturation with water in a single action.

After undergoing meiosis, the resulting Hair Nimbus cells will proceed to divide a few more times, forming spore-like cells which are very small and do not cling to neighbors. Cells in this stage can survive falling as rain and can reenter the sky through dust storms or sea spray. They are dormant until they bump into larger aeroplankton, such as the Cloudbubble. In the case of Cloudbubbles in particular, they are often captured by the sticky feeding tendrils, but if they land on a different part of the plant, they will proceed to start dividing, growing out from the chosen surface to form their namesake filamentous colonies. This does not harm the host plant, as they use UV light for photosynthesis and are transparent in the spectrums that most plants use. Unlike in typical cell colonies, but as is typical for the Nimbus lineage, the cells are not connected by their main bodies, instead clinging by their fronds. This makes them very light, but it also makes the colony susceptible to fragmentation. Broken lengths of colony can rarely reattach to a new host, but they are more likely to collide with other colony fragments in the sky, allowing them to mate. Fragments that never meet other fragments or hosts will eventually die, either of dehydration, predation, or falling as rain, though they have a chance to survive the latter and return to the sky if they land in the ocean or in dry dirt or sand and their fronds aren’t too severely damaged.

There are many species of Hair Nimbus. They often have different adaptations for different parts of the atmosphere. They cannot rise as high as the stratosphere, but they do exist in the upper troposphere. These high-altitude species, along with those residing in polar high winds, employ antifreeze proteins to protect themselves from the frigid air. In general, the width of a hair nimbus cell will decrease in wetter parts of the sky, as they are more susceptible to becoming rain and having shorter fronds makes them more likely to survive the fall. For species which live closer to the ground, such as in montane environments, the aforementioned dangers of rain and dehydration do not necessarily apply, so these are often the largest and fastest-growing species and they typically mate on the ground. Some species of Hair Nimbus are also capable of diazotrophy, fixing nitrogen in the air and the increasingly “lush” clouds to help themselves grow. Not every species does this, but their existence makes them a vital addition to the third sky ecosystem.