The polar ukback split from its ancestor the ukback and spread across the western beach so of Drake and Darwin. It has not grown any longer but has grown much fatter. Its fat helps keep it warm in polar environments. It has lost its back sail but has gained more back spikes to protect it from predators. Their tail-clay now works like a third foot. They now walk like an inchworm, with the front legs then the back tail.
The claws on their head are used only for fighting over mates. Those with more powerful claws will be able to mate. They no longer need to go to the water to lay their eggs. Their eggs now how a soft shell that can be burred in the sand much like sea turtle eggs. They lay them on the first full moon of the spring in mass. This way the babies will have a better chance to survive. They do not take care of their offspring and they must survive on their own when they hatch. Like their ancestors the offspring hatch as a larva phase which resembles a uksip terricola.
They feed using their harpoon-like tooth. This harpoon-like tooth is hollow and it will use it to get through its prey's exoskeleton. Once inside it will inject digestive juices to cause their insides to turn to liquid. Once the insides are liquefied they can easily drink it out. They will also use this to suck out the yolk of eggs. To keep inner liquids of its prey from freezing it also injects anti-freeze like chemical.