Beach Arthrothere
With competition making the Arthrothere's life a daily struggle, it was no surprise for them to rapidly take up niches that would lessen the burden placed on them by competition with other omnivores and herbivores. Some arthrotheres have found some refuge from the chaos of East Glicker Tropical Coast on and near the unforgiving shore.
Like their less-heavily derived cousin, the beach knightworm, the beach arthrothere had little trouble adapting to a terrestrial environment. Their thick carapace and double-nucleated cells allow them to weather the tide of ultraviolet radiation that bombards the surface. Meanwhile, their deeply recessed gills prove difficult to desiccate. Their gill chamber has adapted into a multi-chamber sac filled with gill filaments capable of exchanging oxygen from the air. Their location deep in the abdomen makes them virtually impossible to desiccate and allows them to live on land for an indefinite amount of time. Their endoskeleton has advanced further, with the lower exoskeletal ridge separating and being modified into a sort of spine. Between the segments, specialized vertebrae work in tandem with extensions of the leg exoskeleton to form primitive joints that allow the beach arthrothere to support itself on land. In addition to this, their walking legs have become thicker and more capable of bearing their weight, with the swimming fin being atrophied to the point of being vestigial due to a lack of importance.
The beach arthrothere is significantly more docile than its ancestor due to the lack of competition on land. They primarily feed on washed-up carcasses and beachtrops, with them occasionally entering the water to feed on caltrop crystals and colony crystals. They will also feed on washed-up shallowgobs and beach knightworms. While they can easily capture shallowgobs, they have difficulty capturing beach knightworms, as they can easily detect them approaching due to their large size and in the case of early forms, contrasting coloration. As a result, their green coloration has given way to a blue and copper color, allowing them to blend in with their surroundings. They will typically consume crystal flora and beach knightworms by crunching on them with their powerful jaws. Meanwhile, softer prey is consumed by picking the prey up with its claws. It will then move the prey into the mouth, where it will be consumed. They have greater difficulty moving shelled flora and fauna into the mouth, as they have difficulty gripping them with the claws. They are unable to feed on saltrops due to the excessive amount of brine they contain. A beach arthrothere unlucky enough to feed on one will typically die from exposure to too much salt.
While the beach arthrothere has been able to succeed in surviving on land with relative ease and little modification, it had greater difficulty with reproducing on land. This has resulted in a radical change in the female reproductive system. A section of the female reproductive tract has been expanded to form an egg chamber. This chamber will fill with eggs too large to easily leave the female reproductive tract. Meanwhile, the male has developed the ability to use the ends of its respiratory system to push a sperm-laden fluid into the female's reproductive tract, which will flow into the egg chamber. There, the sperm will fertilize the eggs and shortly after, the egg chamber will close itself off via sphincter and begin filling itself with a nutrient-filled fluid. There, the eggs will develop inside the female until they hatch. The young will then prod the sphincter closing off the chamber, prompting it to open and release the young out of the female's reproductive tract. Females will typically produce 4-6 offspring, which are about 1.5 centimeters long at birth. The young will feed on detritus and small carcasses until they grow large enough to feed on living organisms, starting with shallowgobs and caltrop crystals.