#protist

here are all the resources they provided 🔗:

🌈 slime education! 🦠 🧫

When it comes to Nereus, my general goal is to make something that, while drawing inspiration from Earth, is very distinct from it. One principle I try to implement is to primarily use traits that have convergently evolved multiple times on Earth. There are absolutely times that I violate this (mostly because I think a particular trait is very cool) but it's something I try to keep in mind.

The two forms on the left are algal analogues. The top one is a polystipitate representative of a clade which I don't yet have a name for, although I am considering either Gyrophyta or Discophyta. I've shown them before in a previous post, but their gist is that their "blade/lamina" grows in a ring around a stipe, a morphology inspired by the real world green alga Acetabularia, although these guys are multicellular unlike the unicellular Acetabularia and can also grow much larger. Ancestrally, their "blade/lamina" is disc-like and round, but many forms have divided into essentially a ring of blades connected at the base, which allows it to better bend with the current and thus reduce drag. This can be seen better in the previous post. The form shown here has many stipes (stem-like structures), each with their own blade, attached to a single holdfast, which I have termed polystipitate for my own convenience. As far as I know this term is not used in actual science.

The bottom algal analogue is a particular morphology I came up with for a surface floating (neustonic) algal analogue. I originally designed it with the idea that it was a member of a clade of algal analogues that were composed of giant single cells with many nuclei (multinucleate), similar to siphonous green algae, but upon further thought I think it makes more sense for it to be a member of the Gyrophyta/Discophyta that became neustonic and lost its stipe. I still like the idea of a floating giant single celled algal analogue though. My idea for how these organisms would float would be through a structure similar to the pneumatocysts of (certain groups of) brown algae located in the centre, but of course that raises the question of whether it's likely for such a trait to convergently evolve seeing as I don't know if it's occured more than once on Earth.

The right side consists of three representatives from a group with a very unique place in this world. From the beginning of working on Nereus I've been dubious about including an animal analogue clade. Animal analogues are generally the main focus of most spec-bio projects as far as I've seen, but Nereus has always been more focused on things like algal analogues, chemotrophs, etc. and so I felt like adding an animal analogue clade would distract from the kind of spec bio I actually wanted to do, plus it felt like it would make Nereus a little more Earth-like than I wanted it to be. On the other hand, though, I was uncertain whether or not a world without animal analogues to graze on/disrupt the growth of microbial mats would allow for forests of large algal analogues as I had hoped, as I didn't know if the growth of microbes in the mats would have bound up too many nutrients for the algal analogues to reach very large sizes. Ultimately, though, I ended up somewhere I liked even better. The animal analogues of Nereus were to be giant single-celled amoeboids. The concept for these organisms was inspired by Myxogastrid slime molds and the giant testate amoeba Gromia sphaerica. "Giant" might be a bit of a misleading word, as I imagine they would typically be under 30 cm across, but they would be enormous for single cells.

The bottommost one represents a pretty general morphology for this group. Forms like this would include mat grazers as well as those that feed on large organisms like seaweed size algal analogues as well as other giant amoeboids using pin-like pseudopodia to suck out their cytoplasm similarly to the Vampyrellids, at least as I currently have it planned.

The middle one is a worm like representative which would burrow through the sediment feeding on microbes. I'm unsure how feasible this is for a single celled organism, especially at this scale, but the worm-like Trachelocercids live in the water between grains of sediment, though I don't know if they're really comparable.

The top one is a sessile representative that lives within a shell and extends out very thin pseudopodia (filopodia) through tiny holes in the shell to catch food particles. These hole filled shells with pseudopodia extending out are inspired by Radiolarians and Foraminiferans. My current conception is that these shells will be made of the mineral celestine (strontium sulfate), which is inspired by Acantharian Radiolarians that also make their shells from celestine. I am uncertain whether it's reasonable for them to be able to make such large shells out of celestine since strontium is found in relatively low amounts in seawater. Although I do plan for Nereus to have oceans that are more saturated, I still feel like it would be more reasonable for them to use a more common substance. Maybe I'll have them use a mixture of celestine and another mineral like calcite, aragonite, silica, or apatite.