Why it evolved

The sharp salinity shifts in the Tethys Shallows necessitate an adaptation to maintain osmotic balance. The Salinavigator has evolved specialized internal mechanisms, akin to osmoconforming physiology, allowing it to tolerate a wider range of salt concentrations without expending excessive energy on active ion transport. This is aided by a thickened skin to further reduce water and ion exchange. The trade-off is a reduced gill surface area, making them more vulnerable to low-oxygen conditions if they were to leave the relatively well-oxygenated surface waters of the shallows.