A Primer on Terrapene carolina, the Eastern Box Turtle

Eastern Box turtle partially withdrawn into its shell
A slightly annoyed Eastern Box Turtle.

Everyone likes box turtles. Ubiquitous to forest, farms and suburbs throughout the Piedmont, enjoying a good basking spot on a road or trail, refusing to behave like a proper water-loving terrapin, and a habit of boxing up instead of running allows an average human on an average hike opportunity for a close examination. The turtle doesn’t care much for being examined, but it’s so hard to resist picking them up and looking into their little turtle faces. Also it is fun to knock on their shells to see if they are home. As said before, everybody likes box turtles.

Box turtles, genus Terrapene, are North American based land-modified terrapins, . Their ancestors were proper pond turtles of family Emydidae, which still contains Terrapene. They lived in fresh water ponds, with a flatish shell and webbed feet adapted for swimming. The oldest identifiable box turtle fossil dates to around 15 million years ago. Sometime prior to that point, a group of Emydidae moved to land, lost the webbing, and became more generally spherical. And that’s our guy.

They are called box turtles due to a hinge in the plastron. The hinge allows them to lose themselves entirely. Some box turtles have a hinge to cover their tails too.

There are six species of Terrapene, with between ten and fifteen subspecies. They are differentiated by markings, shell shape, and somewhat by habit. Note that biologists being biologists, this can change. You can make a good guess on which particular box turtle you have encountered based on geography. The one you will find in the Piedmont is most likely Terrapene carolina carolina, the Eastern Box Turtle.

About Eastern Box Turtles

head of female box turtle showing brown eye
Female box turtle, © 2001, John H. Tashjian, California Academy of Sciences. (eol.org)
Head of male box turtle showing red eye
Male box turtle. 2004 National Park Service (commons.wikipedia.org)
  • Sexing box turtles is pretty easy. Females have brown eyes, males have red. The plastron on a male turtle also is indented (this works for most turtles). You can’t observe this without flipping the turtle, which they would rather you didn’t do.
  • They are known to live at least 120 years. Maximum longevity is unclear.
  • They can be semi-frozen, surviving -2 C for 44 hours. Seriously. Somebody did this. Somebody needs a new hobby.
  • Box turtles will eat pretty much anything: plants, mushrooms, worms, the occasional toe on a dead guy.
  • They will sit in place for weeks for no obvious reason, apparently. just contemplating life.
  • They are extreme homebodies. Home ranges can be less than an acre and they will attempt to return home if dislodged. So please leave them where found. Even the little ones. They’re fine. If they’re on a road, you can move them off the road in the direction they’re going.
  • Sex determination is controlled by nest temperature, with females requiring warmer nests.
  • Counting scute (carapace scales) will sort of indicate age, and sort of won’t.

Let Them Be

Box turtle populations seem to be going down drastically. The causes seem to be the obvious ones: new development, being hit by cars, being bit by dogs, people collecting for sale. However, a new hiking trail can also decimate turtle numbers. Well meaning hikers pick them up, give them a pet, let dog harass them, maybe take them home, knock on the shell to see if anyone’s home, and generally bother them. It’s not just gas stations and housing developments; it’s general stress. If we could let them be, they’d actually survive well in suburban areas. So enjoy your surprise box turtle from a bit of a distance. Your great grandchildren may encounter the same one on the same trail some day.

Next week, musk and mud turtles, aka, the little football guys on the pond edge.



Dodd, C. K. Jr., North American Box Turtles. 2001. University of Oklahoma Press.

“Eastern Box Turtle.” Wikipedia, available from http://en.wikipedia.org/wiki/Eastern_box_turtle. Accessed 24, March 2014.

“Terrapene carolina carolina.” Encyclopedia of life, available from http://eol.org/pages/1263662/overview. Accessed 24, March 2014.

What is a Turtle?

Rocks with legs. Armored lizard guys. Got scales, sometimes lives in the water. You’ve got a good idea of what a turtle is.

But let’s do the whole chain (also called a phylogenetic tree), starting with turtles are alive:

Child's drawing of a turtle
Dara K of Hawaii drew this anatomically correct turtle in the second grade for NOAA.
  • Life Figure this out for yourself. You are entitled to the conversation about if you bang two rocks together to get little rocks, is this reproduction?
  • Cellular organisms There is an inside and an outside, a fatty layer between the two, and inside has a bunch of floaty bits to make the cell work. There’s not much structure; it’s just a bag of bits.
  • Eukaryota The cells have a nucleus with the genetic material packed inside, and there are other complicated organelles (mini-organs) that each form particular functions. You can think of eukaryotic cells as a big simple cell eating a bunch of other smaller simple cells, but the smaller ones stay intact. There’s a lot of structure.
  • Opisthokonta They ingest food like fungi instead of making it like plants.
  • Animals They ingest their food in a particular way-this is actually mostly chemistry, nothing to do with using forks or behavior. Think less morality, more ATP.
  • Bilateria They are split into two mirror halves, a left and a right side, with a head at one end and an anus at the other. 
  • Deuterostomia As an embryo, the anus forms before the mouth while changing from a ball to a tube-this is you too. Remember your butt showed up before your brain. This may explain a lot.
  • Chordates A central nerve runs from tail to head. 
  • Vertebrata The central nerve is protected with a spine or version thereof.
  • Gnathostomata The head has two pieces: a skull and a jaw.
  • Osteichthyes The bones are calcified.
  • Lobe-finned fishes The boney legs have hands/feet/paws/flippers. No fins. Legs.
  • Tetrapoda There are four of these legs.
  • Amniotes A nifty filtering layer called an amnion protects the embryo.
  • Reptiles The eggs have a waterproof shell and their skins are scaled. The reptiles, not the eggs. Eggs have a shell. So there’s a two-fer trait in this division.
  • Diapsida Not counting eye and ear holes, these are extra auxiliary holes, two extra holes form in their skull around the temple. They’re called foramen, in case you want to be fancy. Or even fancier than just using “diapsid.”
  • Testudinata The auxiliary skull holes have sealed up, and the ribs have grown tougher to make a solid shell. This is now a turtle.
  • Testudines A modern turtle, not a weird prehistoric turtle.

Turtle vs Tortoise vs Terrapin?

A red eared slider sitting on a rock in an aquarium
A terrapin named Paul, sitting on a rock.

Technically, turtles are salt water based testudines with flippers, tortoises are land based testudines with elephant like legs, and terrapins are fresh water based testudines with a webbed foot. Sometimes terrapins experiment with alternative lifestyles, like the local Diamondback Terrapin that lives in coastal areas, sometimes salty, and the Box Turtles, which are actually terrapins (look at the legs) but walk around acting like tortoises. It’s all about the legs: flippers vs elephant feet vs webbed feet. As for the group, no one uses testudines outside of herpetologists, but in general, American English uses turtles for all of them, British English uses tortoise. No one uses terrapin for the whole group.

Other Turtle Vocabulary, and Some Interesting Things

The shell has two parts: the back part of the shell is the carapace and the belly part of the shell is the plastron. They’re grown solid together, but they are separate sets of bones.

Turtles, along with birds, other reptiles and the monotremes (platypus and echidnas) have a single “out” called a cloaca. Eggs, sperm, feces, urine (or their equivalent-chemistry is a bit different than human pee) all depart from the same door.

Turtles can breathe through their butts. It’s called cloacal respiration. Seriously. They can shunt the blood supply away from their lungs to the lining of the colon then pull water through their anus. It doesn’t give a lot of oxygen, but it does give enough for a sedentary existence, allowing them to hibernate in pond bottoms.

Baby turtles are can be squishy. It takes a bit for the shells to completely ossify. Also they are fine outside. They know what they’re doing. Don’t try and save them. You are welcome to move a turtle off the road, but always put it on the side it was trying to get to. Turtles do not change their minds.

Turtles don’t have teeth. They mostly have a beak like chicken. But some have pretty dang interesting tongues.

Thus ends your turtle primer. Next week, box turtles.

Turtles of North Carolina

There are four distinct species of turtle here, and two more in the pond itself. At least. Could be more. They’re sneaky.

North Carolina is a state full of turtles. Damn turtles everywhere. The combination of being old (parts of the Appalachians are older than plants), never having been flooded properly (parts of the Appalachians have NEVER been underwater or iced over since before plants) and having a crazy number of environmental niches (particularly muddy ponds), lets critters speciate all willy-nilly. So, there’s a lotta different kinds of turtles in the Piedmont. 19 are listed in Reptiles of North Carolina. 5 of those are sea turtles (Leatherbacks/Dermochelys coriace, Loggerheads/Caretta caretta, Atlantic Hawksbill/Eretmochelys imbricata imbricata, Green/Chelonia mydas and Atlantic Ridley /Lepidochelys kempii) so can be ignored as not being relevant to the Piedmont. But at least they are mentioned here.

A white loggerhead turtle
Nimbus, an albino loggerhead held at the Pine Knoll Shores Aquarium

Turtles are distinct. Four legs with a shell (mostly hard, rarely leathery), and most people figure out what a turtle is as toddlers, about the same time they figure out what an orange is. And in this case, the morphology works: turtles look like turtles and things which look like turtles are turtles and there’s really nothing tricky going on. Turtle/tortoise/terrapin is another matter, but the only thing you’re likely to confuse with the group is a rock. If confused, check for a head. Or movement. However, if things other than the turtle/rock are moving, you may be experiencing an earthquake.

So, for completion, here’s the list of the turtles found on land, particularly in the Piedmont of North Carolina:

  • Chrysemys picta picta, Eastern Painted Turtle
  • Clemmys buttata, Spotted Turtle
  • Clemmys muhlenbergii, Bog Turtle (only in the Appalachians, and endangered)
  • Deirochelys reticularia reticularia, Eastern Chicken Turtle (down in the Sandhills)
  • Malaclemys terrapin, Diamondback Terrapin (Coastal only, also endangered)
  • Pseudemys concinna concinna, Eastern River Cooter
  • Pseudemys floridana floridana, Florida Cooter (more sandhilly)
  • Pseudemys rubriventris, Redbelly Turtle (only around the Pamlico Sound area on the coast)
  • Terrapin caroline caroline, Eastern Box Turtle
  • Trachemys scripta scripta, Yellowbelly Slider
  • Kinosternon baurii, Striped Mud Turtle (more coastal, and rare)
  • Kinosternon subrubrum, Eastern Mud Turtle
  • Sternotherus minor pelter, Stripeneck Musk Turtle
  • Sternotherus odoratus, Common Musk Turtle
  • Apalone spinifera spinifera, Eastern Spiny Softshell

Next week, basics of turtles, including some notes on what the dang names mean. And then on to some species descriptions.

Snakes comin’ out.

Cheap, mouse eating cat toys!

Got into the 80’s this week. It is now reliably warm enough for the snakes to come out and amuse house cats by laying across the front porch. And an amused house cat is unlikely to misbehave, so in general this can be considered a good thing.

In case you’re wondering, they are black racers. Harmless, but seem to be more aware of people than most snakes, so you may hear about them chasing you down. They don’t. They will half stand up and take a good look at you though.

Hurry and Catch the Bluets!

Houstonia cerulean. Little dudes are about three inches high. Maybe two. Anyway, they’re tiny.

Bluets, Houstonia ssp, are still in bloom all along the trails. They are blue, tiny, like the damp, seem to enjoy growing in the middle of a trail in an attractive clump of moss and are honestly about the cutest little thing you’ll ever see. There lots of different bluets; 78 species worldwide according to one count, three in North Carolina according to the North Carolina Native Plant Society. The bigger of the ones I find are Houstonia caerulea, which you can know due to the yellow middles. These are listed as “azure bluets” as a common name, as is “innocence” and “quaker ladies”, but the different species are so similar that the need for a particular common name for this flower seems a bit unnecessary. There is another bluet, about half the size, without a yellow center and a darker, more purply blue, but I don’t know which one that is. They also seem to like the sun a bit more than H. cerulea. So, just call ’em all bluets, and if you need to talk about a particular one, use the latin.

Just get over avoiding proper names, people.


“Houstonia caerulea.” Encyclopedia of Life, available from http://www.eol.org/pages/1095514/overview. Accessed April 22, 2015.

“Houstonia caerulea” North Carolina Native Plant Society, available from http://www.ncwildflower.org/index.php/plant_galleries/search_details/houstonia-spp/. Accessed April 22, 2015.

Pinus virginiana, the Virginia Pine

Picture of a Virginia Pine
This tree needs a haircut.
Thanks for the photo, wikipedia.

Virginia Pines are messy. Just generally messy lookin’ trees. Walk through the woods, see a pine, think it needs some trimming’, it’s probably a Virginia Pine. Unlike the other three common Piedmont Pines, they don’t self prune, meaning that they keep their lower branches even after they’ve stopped being of any use and are in fact dead. It’s really the easiest way to ‘id them.

The cones look similar to a Shortleaf’s, and they have two needles per fascicle, also like a Shortleaf. But Shortleaf are generally neater looking trees, with a nice bare trunk. So go with that.

Pinus palustris, the Longleaf Pine

Pinus palustris, the Longleaf Pine, gets the most press of the Piedmont Pines. First, it has a seriously important history. Second, it requires fire to survive in any abundance. Third, it has HUGE cones. Seriously big cones. Bigger than your hand, unless you’ve got abnormally large mutant hands. Otherwise, they are about the same size as the other pines in the area. Oh, and yeah, it has long leaves/needles.

Mature Pinus palustris

Longleaf used to be the dominate tree in the Piedmont, but since European colonization they have steadily been replaced by buildings and more commercially profitable trees. They were heavily harvested in the 1700’s, being common (at that point), straight, and not so branchy, so if you needed a nice straight, long, round log, this was your tree. But that was centuries ago, and now you will not find one without a good search. It is listed as endangered by the IUCN.

They also require a good solid fast burning ground fire to get going. People have a tendency to resent good solid fast burning fires and put them out. So they’re not doing so well. But if fires are allowed to naturally occur, or maybe occur with some encouragement, they can come to dominate. The enormous cones release their seeds more vigorously after a good burning. The seedlings can spend five years or so as a little poof ball of on the ground needles, building up the necessary strength to outpace a fire. After half a decade of poof-ball, the seedling will make a rapid break for the sky, growing six feet or so in a single season.

Pinus palustris has very flakey bark

The needles are in (usually) bundled in threes, just like Loblolly pines. So the mnemonic of “number of needles in a bundle being sorta equal to the number of syllables in the name, as long as you don’t move much away from central North Carolina” doesn’t entirely work. But the needles ARE surprisingly long, so between that and the giant cones, you’re probably good.


“Pinus palustrus.” Encyclopedia of Life, available from http://www.eol.org/pages/323452/overview. Accessed February 5, 2016.

Pinus echinata, the Shortleaf Pine

Pinus echinata, the Shortleaf pine, is another common pine tree in the Piedmont. They are very similar to Loblolly pines. Both trees are tall, thin and have no branches on the lower part of the tree. The easiest way to discern between the two is to find a cone, but this can be annoying if a tree of each species is next to each other, what with the cones falling and rolling about. Anyway, here’s three ways to differentiate between the two:

1. Shortleaf pines have smaller cones than Loblollies and are not spiky. You could throw them at somebody and it would be just annoying, but no blood would be involved. Loblolly tossing will get you cussed at.

Short leaf 2
This bark will hide nothing. Maybe some small bugs. Also it appears to have zits.

2. Shortleaf bark sometimes has these cool little zit like bodies called pitch pockets. But not always. Sometimes they will ooze.  But not always. It is also thinner. You cannot hide a the end of your finger in it. Loblolly bark is thick and corky, and doesn’t have any acne issues.

3. Shortleaf (two syllables) has two needles bundled together. Loblolly (three syllables) has three needles bundled together.

Now you’re good as long as the forest is only allowed to have two species of tree.

“Pinus echinata.” Encyclopedia of Life, available from http://www.eol.org/pages/1033598/overview. Accessed January 18, 2016.

Pinus taeda, the Loblolly Pine

Loblolly 1

Pinus taeda, the Loblolly pine, is probably the most common tree in the central Piedmont of North Carolina. (Okay, found a note saying that it “accounts for over one-half of the standing pine volume” which sounds pretty damn common.) Or if not the most common, at least it is damn common. They are large trees, getting well over 100 ft tall, but sort of skinny. They’re “self-pruning”, meaning they drop their lower branches as needed. So the trunk is nice and clean looking, with a poof of needly branches at the top above the roof of a two story building.

Loblolly 3
The bark is as thick as the end of your finger, dependent upon finger size.

The cones are really spiky, oblong and about the size of an orange. It is the most painful cone to pick up locally.

The needles come bundled in threes and are a little longer than the cones.

The bark is dark and sort of reddish, and broken into scales larger than your hand. Unless you have really big hands.

Loblolly 2

And there you go.


“Pinus taeda.” Encyclopedia of Life, available from http://www.eol.org/pages/1033636/ov