Having survived the shrew plague unaffected and unhindered, the river shrews have been left to continue their evolutionary pathways. Despite a large amount of space opening up before them with their brethren gone, many of these river shrews continued to adapt to their current watery habitat, becoming significantly more advanced, creating the shrotter. Despite this, there is still enough food for both species to continue to co-exist.
Their snout is now longer and thinner, and full of teeth that have become long and fang-like, to better suit catching the slippery-skinned filtersquids, the bristlesquid and the fursquid, that inhabit the area. On the tip of this tweezer-like snout, the nostril area has become bulbous, allowing them to breathe at the surface without ever revealing itself above water. Also to aid in hunting its prey, it has become longer and more flexible, almost serpentine in appearance. The toes on the hind legs are now significantly more webbed, with longer toes, and the claws on these same feet have all but disappeared, as they no longer serve any real purpose. An extra toe has also grown thanks to polyphylangi; however, this toe remains minuscule and unused.
Due to their increased survivability in the water, they have distanced themselves from their ancestors, and now dig their burrows underwater. Because the mud below the water's surface has a weaker consistency than that on land, they will support the den's tunnel by stealing a runanchor's stolon-crystals, to embed into the mud as they work on digging it out. Without opposable thumbs, they've been required to instead bite through the stolon's thin stalk to get the crystals; this is done by having a few of their back teeth remain regular and sharp, having not thinned out over time. Even with this, it generally takes a shrotter a few tries to successfully cut a stolon off.
Although the burrow entrances are below water level, the lairs within certainly are not, and many times are lined with runanchor leaves to aid in the cushioning and even the stability of the floor. Although some dens opt not to do this, all dens will have at least a temporary pile of runanchor leaves when there are pups within. The shrotters seem to only come to land in order to eat their larger meals, as their fore claws are not capable of grasping. Immediately after finishing, however, they will return to the waters. They are occasionally found in the Ichthy Swamp, where they will feed on spraying silverlings and, if hungry enough, swamp hunters.