Lungless Salamanders

     When I was a boy, I would occasionally find an interesting, little red-backed salamander that was under a rock, log or piece of bark I turned over in the woods.  Some red-backs didn't move, instinctively relying on camouflage to conceal them.  Others quickly scuttled under other shelter.  But all were thin and lived in moist, dark places. 
     Red-backed salamanders are one species in about 215 kinds of Plethodont, or lungless, salamanders in the world, the largest family of salamanders on Earth, and the most diverse.  Most of them live in eastern North America, and some species live in Central America and parts of northern South America. 
     Some scientists believe Plethodonts originated in the ancient Southern Appalachian Mountains, more specifically in the wooded Great Smoky Mountains.  Today about 30 kinds of plethodont salamanders live in the Smokies, more species than any other single place on Earth.  In fact, Weller's, pygmy and Appalachian woodland salamanders still live today exclusively in little pockets of spruce/fir forests on some peaks of the Smokies. 
     But in their travels, as species, over hundreds of millions of years, many types of lungless salamanders have spread themselves into many different niches over a broad landscape.  With each species occupying a distinct niche, competition for space and food among these related Plethodont salamanders is reduced.  Indeed, Plethodonts' spreading into different niches caused the many species of lungless salamanders we have today.  Some species today are fully aquatic, others are partly aquatic like two-lined, dusky and red salamanders.  But most Plethodonts, including red-backed and slimy salamanders, are completely terrestrial, another trait their family is noted for.
     It is not known why Plethodonts became lungless, but that characteristic did the ancestral Plethodont no harm.  Now all its descendants have no lungs, but "breathe" through their thin, moist mouth linings and skins.  Lungless salamanders generally are about five inches long and have large, appealing eyes that allow them to see well in dark places.  They are quiet, inoffensive, but always appear alert.  And many species have lovely colors and color patterns.  Females lay little clusters of eggs in moist, protective spots under objects on woodland floors.  There the females wrap themselves around their eggs to protect them.  Their young do not pass through the aquatic stage like most amphibians, but rather hatch on land as miniatures of their parents.
     Land-based, lungless salamanders are highly successful in many woodlands across eastern North America.  Because of their tremendous numbers, they are the dominant vertebrate biomass, by weight, in those woods.  
     There could be many more kinds of Plethodont salamanders in the future because of human activities and habitats.  Because this large and already widespread family of salamanders is not tied to water to spawn, the many species inhabit woodlands across North America.  But our activities have fragmented many forests into smaller woodlots, surrounded by cropland, malls and expressways, built habitats that small, slow, moist salamanders can't cross.  Those human-made habitats cause geographic isolation to many little patches of woods and some of their inhabitants, including land-only, lungless salamanders, such as red-backed and slimy salamanders.  Any favorable quirk in the gene pool of an isolated population of salamanders will stay in that gene pool.  No salamanders of the same species can get into or out of that isolated gene pool.  New species of lungless salamanders may be "born" in many woodlots surrounded by large, dry human-made habitats.
     Land-based Plethodonts are preyed on by a host of small critters among the mosses, ferns, May apple and fungi-strewn forest floors.  They are eaten by American toads, the small garter, brown and ring-necked snakes, shrews, skunks and other creatures.
     Lungless salamanders are attractive, interesting little animals under logs and leaves on woodland floors.  And some kinds today may be evolving into new species in isolated woodlots.  Salamanders, like all amphibians, are relic animals from the distant past.  They are a reminder of the first vertebrate critters on land and how many of those critters lived on land, but spawned in water.