Eartheater
Splitting from its ancestor, the Eartheater has further adapted to a terrestrial existence, in that it has evolved to exploit a subterranean existence. Burrowing through soft soil and moist earth, it claws its way through the dirt with two relatively powerful counter-arms, which are lined with thicker, specialized claws on their outer sides. Functioning somewhat as spades, they catch onto particles of dirt and such with ease, allowing them to dig quite efficiently as each of their counter-arms move opposite of one another.
Eartheaters are herbivorous. While tunneling through the dirt, they will readily consume whatever potential food they should come across. This typically involves bits of detritus or larger bits of decaying floral matter that have become buried under the topsoil. When they encounter such a piece, they will latch onto them and curl up in order to fully encompass them. Eartheaters will also congregate around the roots of various flora, latching onto them as they slowly "erode" them beneath the repeated slicing movements of their inner rows of hooks. In high enough numbers, they can outright kill these flora by destroying their root systems. As is readily apparent, unlike their ancestors, this species can consume food while out of the water, and can readily engulf sufficiently shredded food items with little difficulty.
The vision of Eartheaters has improved in the sense that they have evolved more photoreceptive patches on both the inner and outer parts of their counter-arms. Their function is simple. Should they detect light, then the Eartheater knows it is too close to the surface and will immediately begin to dig deeper. This helps them to avoid desiccation, for though their skin is better at retaining moisture, it still won't do much underneath the harsh rays of the sun.
Respiration and their tolerance for arid conditions are still limited by their amphibious ancestry, though the species has taken some evolutionary steps to overcome it. While still requiring moist soil to burrow through, their skin has become thicker in order to mitigate water loss and thus they are able to tolerate drier soils. However, this also means that their capacity to oxygenate their blood, via transfusion through the skin, is reduced. Thus the species has evolved a "land gill" of sorts, which consists of two pairs of slits located on their inner portions of their counter-arms. If pulled back, porous-looking patches of flesh are revealed, composed of numerous spiracles that suck in air. A small chamber connects directly to them, within which oxygen can be infused directly into the blood while CO2 is defused out. While this is not the most efficient system of respiration, and will certainly limit the maximum size of their future descendants, it allows the Eartheaters to exist on land where their ancestors could not. Eartheater larvae, though, still rely on absorbing oxygen directly through their skin and as such they are still bound to an aquatic existence.
One of the few times that Eartheaters come to the surface, outside of mating, is when it rains. As the pitter-patter of raindrops hits the surface of the dirt, the Eartheaters sense the vibrations and will dig towards the surface, else they risk drowning in the subsequent sea of mud that is sure to form. During such times they are vulnerable, though the current lack of predators on Huggs Island means that they don't have to worry about for the time being.
Reproduction is relatively the same as it was in its ancestor, however now the Eartheaters will spawn in freshwater sources instead of saltwater ones. Lakes, ponds and streams are all utilized, and adult Eartheaters will swarm into the shallows and proceed to spawn en masse, releasing hundreds of eggs and sperm into the open water, where they intermingle and become fertilized. The resulting larvae behave much like their distant Flatbun ancestors, consuming small bits of detritus and other nutrition until they are old enough to leave the water, whereupon they will instinctively begin to burrow. Besides being capable of undergoing binary fission, Eartheaters can also regrow if they are somehow severed into multiple parts. Displaying a remarkable capacity for regeneration, new individuals can even come about should a sufficiently large portion of one, such as a counter-arm, should remain fairly intact. Should it be able to grow a new mouth and digestive tract quickly enough so as to avoid starvation, the fragment has all the potential to survive and grow into a clone of the original.