Crooknas are beasts of burden and war, first domesticated by the Bermarans, that saw their origins in the Shadowlands. In fact, crooknas remain one of the few Shadowland animal species that have been successfully domesticated and integrated into Celesterran society, due in large part to the efforts of Dunskiff of Berm, who was allegedly the first to make efforts towards their domestication. Today, crooknas are largely the domain of hobbyists and historians, as technological advancements have largely replaced them with less temperamental mounts, but there are still those who claim that no rockskiff will ever compare to a well-trained crookna.
An average crookna stands with its shoulders at about chest-height to the average Celesterran; however, this is due to their horizontal posture, and if considered from their heads to their hindquarters, they typically measure nearly twice as long as an average man is tall. Like many Shadowlands creatures, they are hexapedal; their legs are arranged in three pairs, spaced evenly along their long, insectoid bodies. They have six segments in all: the first sports eyes, mandibles, mouth, and several sensory pores; the second, fourth, and sixth are where the legs sprout from; the third has no external structures save for the rocky carapace that covers most of a crookna and is thus where most riders mount; the underside of the fifth is where the genitals and egg-laying apparatuses are located and is where a second rider will typically mount if necessary; and the sixth segment contains both a pair of legs and mechanisms for waste-elimination, scent-marking, and markings that identify an individual crookna to others.
Unlike many Shadowlands creatures, crooknas are omnivorous, and in fact gain most of their sustenance from vegetable matter. It is likely this trait that made them more amenable to domestication than most such creatures, as their reaction to other living things is more likely to be cautious curiosity than fear or hunger. Most of a wild crookna's diet is likely to be composed of glowcaps and nectarcups, making them rather a nuisance to Shadowland farmers; this is supplemented by the opportunistic consumption of many of the smaller Shadowland creatures, especially chitterlings and fungus-crawlers. A domesticated crookna in the Shadowlands is likely to have a very similar diet, but those who have been moved to Terra Alta have been found to be capable of subsisting healthily on grains and leafy vegetables. Oddly, they have been noted to have severe allergies to every part of the bitterseed vine, making treatment of their ailments and illnesses notoriously difficult.
Crooknas are naturally social, but do not engage in typical "pack animal" behaviors; there has never been any kind of hierarchy observed in crookna groups, and in fact a crookna group is not so much a team as a temporary alliance forged from self-interest and necessity. Crooknas frequently leave an individual group, often spending significant time on their own before discovering another, and sometimes a group will simply disband for little apparent reason. There is no leader of a group; rather, it seems they simply end up doing whatever a majority of the crooknas in that group feel like doing, and dissenters are essentially forced to go along with it or find another group to join.
Unlike bellow reamers and beetlehounds, crooknas are neither interested in nor bothered by moon curtains; there is some debate about whether they are capable of perceiving the curtains at all. Regardless of whether or not they can perceive them, they are certainly not deterred. This makes protecting crops from wild crooknas quite difficult; there are a number of ways to discourage crooknas from entering a farm, but the most popular and consistently successful involves spraying the perimeter with a mixture of water and fermented axenbron urine. The urine contains trace quantities of thellmozen, which the olfactorily-sensitive crooknas can easily smell. While the amount of thellmozen present is small enough that it poses little to no danger to any lifeform, crooknas will almost invariably avoid any detectable quantity.