Why it evolved

Sustained high temperatures, a consequence of extreme heat events, place immense stress on the Frostgill's internal temperature regulation. This descendant has evolved larger, more complex gill filaments that function as heat exchangers, allowing it to shed excess heat into the surrounding water more effectively. This adaptation is crucial given the world's oxygen-poor, cold water conditions, which would otherwise exacerbate heat stress. However, the increased surface area of the gills makes them more vulnerable to damage and potentially less efficient at toxin filtration, representing a significant trade-off.