Siltsifter

Splitting from its ancestor, the siltsifter has further evolved to exploit a subterranean lifestyle. Possessing a smoother, narrower exoskeleton compared to that of its kin, its powerful spade-like forelimbs allow it to quickly tunnel through the sand as it searches for small bits of detritus to consume. With no natural predators, their numbers have exploded, which had led to most beaches throughout Dixon to have populations that are millions strong. Such a population size has affected these regions as well, as their constant burrowing helps to aerate the sand to a small degree, while their waste provides nourishment for various coastal flora and microbes. At night, while under the light of Mason, siltsifters will often surface in order to scavenge corpses that have washed ashore, thus helping to keep the beaches clean.

Unlike their various kin, the siltsifter is still fairly reliant on the ocean in order to survive. Their gills are still present, just as they were in their ancestors. However, they have become somewhat reduced in size and function, but nonetheless must be periodically moistened with water, lest they otherwise become desiccated, which would be fatal due to the resulting suffocation that would ensue. An exposed gill opening would have proven a problem for a subterranean lifestyle, so the species has evolved to counteract this with the evolution of tiny gill flaps that cover them. These gill flaps are supported by bony internal structures, not unlike that which makes up their exoskeletons, and contain a rich supply of blood vessels that tint them purple in color. These flaps aid them by preventing sand from becoming lodged within the gill openings. The connected air sac, located on their backs, still functions as it did in their ancestor, though now, just as with their gill flaps, the amount of blood vessels filling it have greatly increased in size, leading to the purplish hue due to the color of their blood.

Reproduction occurs throughout the year, and the eggs resulting following fertilization are released into the water during high tide so that they may be carried out into the open water with the currents. The larvae that inevitably hatch from these eggs will stay within the open waters, feeding on free-floating bits of detritus until they are both large and developed enough to settle onto the shores of the beaches and begin digging tunnels on their own. This dispersal method has led to the colonization of Fermi island by larvae that, while floating in the Dixon-Fermi Subtropical Sea, were carried over to the shores of that adjacent landmass. It did not take long following this for healthy populations of siltsifters to establish themselves there.