Scarletshell Sandhopper
Taking those first few tentative steps out of their ancestral home that is the sea, the scarletshell sandhopper now encroaches on a brave new world that is dry land. The first in all of their lineage to do so, these pioneers are aided by the air-breathing adaptations of their ancestor, the Chambered Siluro, which now allows them to spend extended periods of time in the open air, though they still need to periodically submerge themselves in the oncoming tide. Should they fail to moisten their gills in a timely manner, they run the risk of them become desiccated and thus unusable, thus a sandhopper can technically drown in the water should this happen. Said gills themselves are both smaller and more vestigial compared to those of their ancestors, as they are of reduced use in adult scarletshell sandhoppers, especially given the changes that have happened in regards to the rest of their respiratory system, which will be described in detail further on.
In order to overcome the challenges of the shoreline, the sandhoppers have adapted by both digging and exploiting burrows upon the shoreline. These homes often contain chambers filled with water that routinely replenish with the high tide, thus allowed the sandhoppers to remain in relative comfort throughout the day as they avoid the heat of the midday sun. Fights over burrows are fairly common, though they mostly just show with two individuals interlocking their tentacle-jaws until one yields and retreats.
When night arrives, and with it the rising of Mason in the starry sky, the sandhoppers leave their burrows and return to the sea in earnest. Their red coloring appears almost black in the dark waters, allowing them to stealthily hunt down prey and avoid predators at the same time. Their relatively large eyes are able to pick up minute amounts of light, allowing them to see in the twilight waters. Due to the lack of food that their ancestors in the region experienced, they have expanded their diets to include the various nautstars and their descendants, as well as something not found in the water itself. On land, they will on occasion attempt to lightly graze upon the plentiful violetpalms and, on rare occasions, the younger specimens of stickymoss that inhabit the beaches that they call home. While their guts have not fully adapted to digesting these flora, they do manage to derive some nutrition from them nonetheless.
As the sandhoppers developed a more diverse diet, so too did their digestive tract evolve to handle it. Perhaps the most noticeable of all these adaptions is the formation of what is essentially an esophagus. No more is the classically geletaventrian gastrointestinal path, which allowed food to potentially spill out. Instead, a fleshy tube surrounded by rings of muscle help to push food down into the stomach while at the same time preventing it from escaping back out. Tiny backwards pointing keratinous protrusions, very much like teeth, line the inner walls of this structure, which helps to prevents more gelatinous and soft-bodied prey, such as oceanic lanterns and the like, from escaping. Because of these adaptions, the sandhoppers can avoid accidentally voiding their gut content, and thus retain vital nutrition that would otherwise have been lost.
In regards to their respiration, several morphological adaptations have occurred that have furthered helped the scarletshell sandhopper take on the challenges of terrestrial life. The unpaired spiracles on the lung-chambers have now become paired, an adaptation that makes breathing easier especially while burrowing through mud or sand as it greatly reduces the risk of suffocation should one or more become clogged with debris. These spiracles are hidden within the gap between the lung plate and the torso plates as a defense against parasites that might otherwise exploit such vulnerable openings. In conjunction with these orifices, the paired gill-chambers - which are connected to the facial nostrils - now open into the anterior lung-chamber, allowing for increased oxygen intake. Said lung-chambers no longer possess the pronounced separation seen in the chambered siluro as they are no longer needed as much for buoyancy. This provides the sandhopper an added benefit, as the separation hindered airflow. As such, for all intents and purposes, the two lung-chambers are effectively one.
Reproduction still occurs in the water and has for the most point not changed that significantly from their ancestors. Their young are still water-bound, feeding on tiny particles of food suspended in the water column, and will only take to the land after several months of life, whereupon they are both large and developed enough to traverse the sand and mud of the shorelines. It is biological requirements such as this which still bind the sandhoppers to the sea.