The Irridalli are a successful group of medium-sized predators stalking the upper levels of Chriirah’s tropical oceans. Like many mobile quadrilaterians, evolution has optimised their four-sided body plan into a sleek, secondarily bilaterally symmetrical shape able to move swiftly and efficiently through the ocean.
Possessing some social intelligence, Irridalli travel in loose pods to locate swarms of suitable food, at which time they separate and attempt to drive the prey nearer the surface, thus rendering them easier to capture. Despite this initial co-operation, the actual hunt itself is performed independently of the other pod members, cooperation only resuming when prey needs to be driven towards the surface once again.
While Irridalli are quite fast, many prey species are considerably faster and swimming speed is not their primary weapon: Moving in behind prey, the large eyes fix on a target and when in range two tentacles launch outwards as an elongated and lethally barbed lower jaw attempts to impale it. If the strike is successful, the tentacles rapidly coil around the doomed creature and draw it towards the mouth.
Like most apex predators, the Irridalli suffered major population depletion in the period leading up to, and during, the fall of birrin civilisation. As the birrin recovered, so too Irridalli populations increased in parts of their former ranges as prey species returned. The loss of genetic diversity however has resulted in higher than expected parasite loads in some pods.
Once hunted by the birrin as food, they are now rarely eaten both because they are widely protected, and are so infused with accumulated industrial poisons they are mildly toxic to ingest.