Puddle Stercor
The Puddle Stercor (Initiasterus conlectus) is descended from populations of Stercors (I. fluminis) which became trapped in pools of water too far from the waterways to be consistently refilled, especially in the dry season. To cope with their puddles drying out, their eggs are coated in mucus, which temporarily protects them from desiccation when the puddle dries up for up to 4 days in optimal conditions. This also makes their eggs capable of occasionally surviving trips through the digestive tracts of fauna which might accidentally consume them when drinking from pools. This is because mucus is also used to protect the digestive tract’s lining from gastric acid and digestive enzymes, so the eggs that were coated in it were shielded as long as the mucus wasn’t washed or scraped off. This was key to this new species fully splitting from its ancestor and spreading all over Zone D.
The production of the mucus which covers the eggs occurs inside the gonads. The mucus is not a solid barrier; sperm could still swim through it at the time this feature first evolved, and they have since developed a corkscrew-shaped flagellum which can push through the mucus more effectively. When the eggs are consumed, such as when a muscal drinks from a puddle, those that are fortunate enough to not have their mucus coating breached by factors such as rubbing against food particles in the organism’s stomach may pass through the entire digestive tract and eventually make their way out in their droppings. If the droppings happen to land in water, such as a new puddle or a pond, the moisture will break up the feces enough that even eggs trapped very deep inside can escape and hatch. The mucus coat is no barrier to the hatchlings, which easily breach it just as they breach the membrane. Nothing is different about their development, and they still take between a week and a month to reach full size depending on conditions in their environment. The puddles are able to support them for so long due to the humid environment over much of their range, though in some regions they only thrive in longer-lasting ponds due to the puddles evaporating too quickly.
Not all Puddle Stercors live in temporary puddles, of course. Some reside in ponds, as mentioned previously, but they can also survive underground in sinkholes formed by subterranean water flow, where they survive mostly off of detritus and microbes which have washed in from above like they were. These populations are as temporary as their sinkholes, which usually eventually open up and either fill in with debris or dry up, but as long as new sinkholes can form, Puddle Stercors are likely to continue to colonize them.
Outside of the mucus-coated eggs, very little differs about the Puddle Stercor compared to its ancestor. It still has a ~500 μm armspan and glides along submerged surfaces in the direction of food using its cilia. Its aversion to bright light still serves to protect it from ultraviolet radiation, but it also allows it to move away from parts of its puddle more likely to be evaporated in the light. It can still change sex at will, but as females produce mucus for their gametes and males do not, this requires more energy and thus it is less likely to change unless there are no others around of the opposite sex. It still broadcast spawns under unfavorable conditions, with fertilized eggs being able to hatch within a day but able to wait as long as 5 if environmental conditions aren't suitable, and reproduces asexually through six-way fission every 5-15 days when food is plentiful. It has no true color and is instead mostly see-through, apart from its eye spots.
The Puddle Stercor is a generalist. It consumes tiny pieces of dead muscals and polyphs, as well as microbes such as V. dissolvus; zoospores and fragments of organisms such as P. khthonspongos and P. woodifungerius; the spores of F. ateras, M. arcaica, and R. litorus; and occasionally its own species’ gametes, eggs, or juveniles.
Within its new environment, the Puddle Stercor does not yet have any non-incidental predators. It does, however, have two especially notable incidental predators which may occasionally eat it while consuming detritus, these being L. cocotus and S. bulbuphagus. However, the muscals primarily responsible for spreading it to new bodies of water through incidental consumption of its eggs are faster-moving terrestrial and flighted species, such as A. gigaslothus, A. migragigas, D. tromerovenator, F. prakerus, J. fucopinna, J. jumpus, K. flavocallus, K. pectoflavus, M. noctevenator, M. ovicomus, O. herbimothus, O. mothus, O. oviyerious, P. diomedeasii, P. pernix, P. polyodon, P. velocius, and P. vorax.