Nightworms
While many large predator niches have already been taken, most smaller organisms of Darwin up to this point have only taken decomposer or primary consumer roles in the ecosystem. However, one derived clade of shed knightworms began specializing in live prey, eventually splitting off to give rise to an extensive and highly diverse genus known as the nightworms.
Nightworms have many new and generally useful adaptations to their environment that are not necessarily related to their feeding behavior. The most useful of these is their large antennae, which are present in all species of nightworm. Higher flexibility in the joints as well as more powerful muscles allow nightworms to use their antennae to walk. While this manner of locomotion does cost more energy, it is much faster and more efficient than their usual method of movement. The antennae also have extra minerals and trace metals, making them slightly more durable than they would be otherwise. Nightworms rarely use their previous method of locomotion, only doing so when trying not to be noticed.
Nightworms’ rate of shedding has decreased, allowing their exoskeleton to grow thicker and more durable as a result, making their cuticle more like that of a terran arthropod. Nightworms are primarily nocturnal, hence their name, and most species have a dark coloration to match. In order to better see their prey in this dark environment, nightworms have evolved large forward-facing eyes reminiscent of terran jumping spiders. In pitch-black environments such as burrows or hollow petrolignum logs, they can also use their long antennae to feel their way around in the dark. All species of nightworm have an extra body segment, as did their primordial thornworm ancestors. This is the result of genetic drift; while the extra segment does give nightworms a slightly longer hindgut, it offers little to no advantage in their environment.
While nightworms primarily specialize in consuming small milesverms such as rolyknights, most nightworms will consume almost any prey smaller than themselves, including other species of nightworm. Nightworms also scavenge to varying degrees, with some species relying entirely on scavenging and others almost never doing it at all. Their primary tool of acquiring prey is their antennae, which are used mainly to grab onto or stab their prey. Most species of nightworm have miniscule serrations on the front and back of their antennae, making them effective at grabbing and slicing through flesh. In some species, these serrations have become greatly enlarged to allow more traction while walking, with said species adopting a gait more like that of a baby sea turtle, as opposed to the tip-toeing motion of most nightworms.
The radula of the nightworm is also adapted for a more predatory lifestyle, with most of the teeth being a curved claw-like shape. Six (or eight) particular teeth on the sides of the radula have become greatly enlarged in order to easily tear off larger portions of their prey. While most species of knightworm would have to lift up their whole head to use such a feature, the snouts of nightworms are shortened and tilted upwards such that the mouth is raised and faces slightly forwards. Many nightworm species also use a mild form of external digestion to make food consumption easier, as their saliva has a high amount of digestive enzymes in it. As a rule of thumb, the species which scavenge have more enzymes in their spit and will secrete more saliva when eating, but there are some exceptions.
Nightworms’ reproduction is the same as its ancestors, making it difficult for nightworms to survive in the desert or anywhere else devoid of ponds or lakes. Many species also retain the ability to dig burrows to hibernate over the winter, allowing them to live in temperate and subpolar areas.