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- Written by Clyde McMillan-Gamber Clyde McMillan-Gamber
Eastern box turtles, Blanding’s turtles, and wood turtles are beautifully colored, camouflaged species in the northeastern United States. These species demonstrate divergence (branching out) and convergence (coming together).
These attractive kinds of turtles have characteristics in common. They live in or near ponds and streams in woods and are omnivorous, eating invertebrates, berries, carrion, and other edibles.
All are active by day and hibernate through winter, box turtles under mounds of dead, fallen leaves and soil and the others in mud at the bottom of ponds and slow streams.
Females of all species lay four to eight eggs in holes they dig in loose soil in June. But many turtle eggs are dug up and eaten by striped skunks and raccoons. Surviving young hatch in August or September.
Box turtles and Blanding’s turtles diverged from a common ancestor. They both have domed top shells called carapaces, which are ribs and backbone grown together, as in all turtles. And both kinds have hinged plastrons, or lower shells grown from sternum bones. Those shells together protect turtles.
However, box turtles live on woodland floors, while Blanding’s mostly inhabit ponds and slow streams in or near bottomland woods.
The muscular hinge on each box turtle’s plastron closes that shell tightly, with the turtle inside. But that same hinge on a Blanding’s turtle’s plastron doesn’t close as tightly.
Blanding’s turtles drop into protective water when threatened. But box turtles can’t do that, so their plastron evolved to close tightly to keep predators out — an adaptation that made a big difference.
Mature male box turtles have 6-inch dark carapaces with yellow, camouflaging streaking and are handsome with orange or yellow scales and skin on heads, necks, and front legs. Female box turtles are not as colorful but still attractive.
Mature Blanding’s turtles have 8-inch carapaces and are mostly dark all over, with yellow throats and chins, and small, yellow dots on their carapaces that almost resemble the yellow streaking on box turtle carapaces.
Box turtles and wood turtles are not related but are similar because they adapted to the same habitat (convergence). Wood turtles, however, spend half their time in slow streams in woods.
Handsome, mature wood turtles have 10-inch brown carapaces with yellow streaking and orange on their necks, throats, and front legs. Wood turtles also have dark, intelligent-looking eyes that are appealing.
All these species, and other kinds of turtles in the world, are decreasing in numbers because of habitat loss, collecting for the pet trade, being killed on roads, and an increase in fur-bearing predators. Please leave wild turtles in the wild.
These three types of attractive, interesting turtles illustrate divergence and convergence. And they are fun to see in their natural habitats.
Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.