The Atlanteans are a genetic offshoot of mainstream Homo sapiens called Homo mermanus,nn who by as yet unknown means acquired various bodily attributes nenablingn them to live indefinitely beneath the sea. The name n"Atlantean" is nderived from the ancient civilization of Atlantis that sank beneath the sea in prehistory, and whose ruins were settled by the Homo mermani. nAtlanteansn possess twin gills located on their necks near the nclavicle bone, nwhich enable them to extract oxygen from the water. They npossess a nphysiology far stronger and more durable than their surface nncounterparts, which enables them to withstand the vast water pressure natn the ocean's bottom as well as the pressure changes encountered nntraveling from one depth to another. Compared to the average nnair-breather, the average Atlantean is about ten times stronger. The nnaverage Atlantean can swim at a maximum speed of 30 miles per hour. nnAtlanteans are warm-blooded, and their blood circulation is superior ton nthat of land-dwellers, enabling them to withstand the near-freezing nntemperatures of the ocean depths with minimal discomfort. Atlanteans nnhave specially-adapted eyes possessing vision more sensitive to the nngreen portion of the spectrum. This enables them to see more acutely inn nthe dimly-lit ocean depths. Atlanteans need water in order to breathe,n nand will suffocate in open air in about five minutes. Atlantean skin nntends to be light blue in color, although certain individuals are nndarker. Atlanteans possess residual body hair primarily on their heads,n an holdover from their surface-dwelling ancestry.