Well, if they are lungless, it isn't as impotant as say a metamorphosing Salamandrid for them to reach the surface.Most Eurycea and some duskies are fully aquatic in captivity and the wild as adults anyway.They breathe through cutaneous respiration, (through the skin)so they will get their oxygen from the water even as adults.Sure the extra land area may be great.But they may not even come out of the water permanently anyway.With no predators in the water in captivity they might not leave the water at all.But the land area is still a good idea incase they are not an aquatic species or are not plethodontids at all.