Duocrurian, Naddis have two legs. These are slimmer than most other Kachik, although they make up for the loss in mass with a far less porous bones, with more than 70% solid mass. They do not have eyesight or any visual cortex structures, instead only being able to feel and taste. This aids them in movement and hunting.
Naddis, like all Kachik are carnivores, and are able to sustain themselves as lithotrophs. They have two, advanced stomachs to be able to digest the variety of foodstuffs that they eat. Their most common prey include small Bitkcirtl and Hecbir, but can also include other Kachik. They rarely resort to cannibalism. Their lithotrophic abilities allow them to eat sand, but also get maximum nutrition from water, making them slightly hydrovorous.
They are reasonably intelligent for Kachik, with encephalization quotients of 1.18. They rely primarily on instinctual action.
The only major difference between Naddis and other Kachik is that they have a large, bony tail which acts as both a prey-finishing club and a counterweight for their heavy chest. Their chest has one, three chambered heart which is supplied by an extremely large lung, capable of holding up to twice of other Kachik's lungs. On average, they measure up to 2 meters in height, and 1.65 meters in length.
Solitary, Naddis live by themselves almost all of their life. They mate once every two years, like Keskidis, but do not have any sort of immediate primary attention towards their young, abandoning them after 2 weeks of care.