Turtle Divergence

     Turtles have lived on Earth before and after the dinosaurs.  They have survived long enough to spread into about every major environment on this planet, from deserts to oceans.  Their use of many different niches has resulted in many species of turtles that don't compete directly for space and food.
Some examples of this diverging into different niches can be observed here in eastern North America.  Interestingly, land turtles have humped-up shells while water turtles have flatter shells for slipping more easily through the water.  Being reptiles, all turtles are cold-blooded, and many of them hibernate through winter's cold.  And all turtles lay eggs on land.  Get a field guide to North American turtles to see the appearances of these turtles and read more about their life histories. 
     Tortoises have adapted to living in deserts and drier habitats in the United States, for example.  They dig burrows in sand, many of which are also used by many kinds of critters, including rattlesnakes, spiders, various insects, burrowing owls, rodents and many other species.  Tortoises mostly eat flowers and other vegetable matter they can reach from the ground.
     Box turtles are handsome land turtles that mostly live on woodland floors.  They burrow under piles of fallen leaves each evening in spring, summer and autumn and hibernate in the soil in winter.  They eat almost anything edible, from mushrooms to berries, invertebrates and carrion.
     Three turtles of the clemmys genus, wood turtles, spotted turtles and the rare bog turtles, dwell in a mix of land and shallow water habitats.  Wood turtles live and feed much the way box turtles do on forest floors, but with more of a tendency to enter woodland streams at times.  Spotted turtles live most of the time in shallow woodland brooks where they consume aquatic invertebrates.  And the diminutive bog turtles live in bogs of clumps of grass standing in shallow, still water.  There they also ingest invertebrates.     
     Painted, snapping and slider turtles all live commonly in the more shallow parts of ponds and lakes.  All these turtles are meat eaters when they are young, but snappers are strictly carnivorous all their lives.  All these turtles bask in the sunlight to warm up to have the energy to look for food and mates.  They hibernate in the muddy bottoms of impoundments through winter.  
     Map turtles and sliders inhabit fresh-water rivers.  Sliders dwell with painted turtles in ponds and live in smaller rivers with map turtles.  But map turtles also inhabit large rivers where they eat mollusks, crustaceans, insect larvae, small fish and other critters.  Map turtles also are devout baskers, sometimes piling on each other on mid-river boulders and fallen trees to soak up the warming sunshine.  
     Diamond-backed terrapins live in Chesapeake Bay, Delaware Bay and other brackish, back waters along the Atlantic and Gulf Coasts, uniquely the only turtles to do so in America.  They feed on mollusks and crustaceans they glean from the bottoms of brackish bodies of water.
     And there are a few kinds of ocean turtles that come close to North American shores.  They are the biggest turtles because the salt water supports their weight.  And they have large front flippers adapted for long distance swimming. 
     Turtles are an interesting example of related creatures diverging into different niches to take advantage of various food sources.  That diverging also creates different species, each of which is adapted to its niche without competition from its relatives.  Worldwide, there are, potentially, as many species of plants and animals as there are niches.