Onahks were semi-amphibious creatures from the temperate wetlands of Osirrag. They had six feet with clawed toes for climbing on land and retractable webbing for swimming. Their most noticeable feature was their long necks, which could extend to a full two meters in length or retract to a mere 30 centimeters. Their sensory organs included sensitive eyes on the ends of their necks and taste and smell bulbs located on forward "long stalks" and rear "short stalks." Their mouths were located on their underside. Though they were primarily water breathers, they could breathe air for up to five minutes, and were as agile on land as in the water.
Onahks were social creatures, traveling and hunting in small pods consisting of two to eight adults with their cubs. Onahks were known to defend other members of their pods even if it meant their own deaths. Their primary food in the summer was small birds and reptiles. In the winter, they would move underwater, retracting their necks against the cold, and hunt fish and quolers.
Though they were generally fearful of creatures too large for them to prey on, some onahk cubs were curious enough to follow Human colonists when they began to settle Ossirag's wilderness. Some settlers domesticated them for meat. Others found that they made loyal and intelligent pets.