The box turtles clean up nicely

April 13, 2021

Here’s Easty dirty, with a dull-looking shell and a pretty serious ‘tub ring’ of hard-water stains around the crown of her carapace. This shot is a few years old, but she looks about the same now when she’s filthy. But here’s how she cleans up:

On Saturday I gave her a good soak in some warm distilled water and scrubbed her shell with a toothbrush. She shined up beautifully. I should have tried shooting a video, because the keratinous scutes on her shell are a bit translucent, and when full sunlight hits them they take on a depth and luster that I had not previously appreciated (heh).

I shot some reference images in the cardinal directions. If you need dorsal, lateral, or ventral views of an adult female Three-toed box turtle, Terrapene carolina triunguis, it’s your lucky day.

The lateral view is interesting, because you can clearly see the joint between the two halves of her plastron, both of which can raise like drawbridges to completely seal her behind an impenetrable wall of bone and keratin. You can also tell that her posterior plastron is gently convex, which is a female trait. As in many other turtles, male box turtles tend to have at least a gently concave posterior plastron, to help them stay on top of the females during mating.

And a ventral view, giving a good look at her plastron. Note her tiny, tiny tail, with the swelling for the vent just visible in the shadow of the plastron, about even with the edge of the carapace — that’s another female trait, whereas males have longer tails and a more distal vent for mating. You can also see yellow lines cutting across some of the scutes of her plastron — those are the outlines of her plastral bones showing through the overlying keratin. As in carapace, the keratinous scutes overlap the edges of the bones to form a sort of biological plywood. A lot of the growth lines have been worn off of her plastron, which is totally normal, but for the most part you can tell where the growth centers were originally located.

I also gave baby turtle a proper bath, with supervision. Baby box turtles can swim just fine, but if the water is inconveniently deep they can sometimes get flipped over on their backs, be unable to right themselves, and drown. She really did not like not having something to haul out on, so I put in the black jar lid you see in the photo. This particular pic is overexposed, which was a happy accident, because now you can see that the apparently dark and featureless areas of her shell and head are in fact very intricately patterned (compare to her dry photo at the top of this post). I’m really looking forward to seeing how her colors come in over the next few years.

And here’s her plastron. Baby turtle is a different subspecies from Easty — she’s a true Eastern box turtle, Terrapene carolina carolina — so she should have stronger patterns on both her carapace and her plastron when she gets bigger. Her head my also be more vibrantly colored, although Easty is no slouch in that department.

I put the two of them next to each other for a very closely-supervised comparison shot. I had been worried that Easty might have a go at baby turtle, but actually the opposite was true. The wee monster frankly terrorized Easty by nipping at her toes –and this was after eating two small slugs from the back yard — so I brought that experiment to a swift end, and got nipped on the finger for my trouble. I happened to be filming when baby turtle nipped Easty’s toe and my finger, and I will try to get those videos cleaned up and posted soon. Watch this space.

22 Responses to “The box turtles clean up nicely”

  1. Brad Lichtenstein Says:

    1. Good thing they’re domestic – by making them shiny, you’ve removed a lot of their camo!

    2. Were they still wet in these pics? Even gorgeous pebbles on the beach get boring-dull when dry, I’ve seen.

    3. If looks could kill… your littlest monster doesn’t seem to like you yet…

    4. Why are they so small – and why are their necks so short??

  2. Mike Taylor Says:

    Plywood is biological.

    Nice photos, though!

    But why no anterior/posterior? You could TNF that bad girl.

  3. Matt Wedel Says:

    Brad — yes, they were still wet in these photos, to show their colors to best effect. As for the small size and short necks, that’s just how they roll. There is a giant extinct subspecies, Terrapene carolina putnami, that got up to a carapace length of about a foot, but any modern box turtle over 7 inches is a whopper and 8 inches is world-record territory. Apparently they just work well at small size.

  4. kris michael Says:

    Have you tried putting them in a rock tumbler for a couple hours? Probably wouldn’t do much for the camouflage. I’ve noticed box turtles look more like dead leaves while tortoises look more like dirt, sand, and rocks. Forest versus grassland/desert. It’d be interesting to compare different species and morphs with their various habitats. And if it changes as they age and move to different environments.

    Their necks are short because they have to fit inside that shell along with the rest of their body. I don’t think they’re like the ones in the cartoons that are scrawny little guys inside with their hot plate, wearing patched up long johns. Probably a lot of intestines in there, I’ve never seen a turtle dissected.

    On that note science has shown that food over 7 inches gets spotted by humans very quickly. Turtle soup is something I need to try, something you can do with yours after you extract them from the rock tumbler. Maybe heat it up with the hot plates..

  5. Brad Lichtenstein Says:

    Lol, so you’re saying that, on your chart of record necks, this alleged gigantic box turtle subspecies would warrant about a pixel. Got it. I should have expected this group to give serious answers.

  6. Brad Lichtenstein Says:

    Actually, in my “looks could kill” comment, I just looked at her (baby turtle plastron) pic again – their eyes seriously cant downwards. Makes sense they need to guide their mouth, and maybe lift their heads anyway to check landmarks, – and still have visibility upwards because her eyes bug out so far! But looking at the bigger cousin, is that because they’ve practically got moveable shell over their eye, and she really is just giving you a death stare? I mean, if you posted pictures of your wife as she stepped out of the shower, I’d expect the same basic “I will stop at nothing to chop you into little pieces” expression.

  7. Matt Wedel Says:

    kris, I had taken Brad’s comment about the short necks to mean in contrast to snapping turtles and softshells, which have long enough necks that if you don’t hold them by the back of the carapace, they can reach back and deliver a wicked bite. Box turtles do have just about the shortest necks, proportionally, among modern terrestrial turtles. And I think the small size is interesting. I’d always taken it for granted, but box turtles are significantly smaller than both North American tortoises (genus Gopherus) and the sliders that they are related to. Same goes for spotted turtles, Blandings turtles, etc., that are in the same larger clade as box turtles. I’m not sure what’s going on there, but whatever it is, it clearly works for them.

    I had turtle soup for the first and so far only time on a trip to Philadelphia a few years ago. I believe the soup I had was made from snapping turtle, and it was delicious. But I probably won’t be repeating the experiment. As someone who likes to try new things I felt compelled to try it, but as a turtle lover I can’t really justify doing that more than once.

    I’ll take your suggestion about the rock tumbler under advisement!

  8. Matt Wedel Says:

    Brad, in my experience most turtles have enough binocular vision to deliver very accurate strikes on their food. And once they decide to bite, the head and neck can move fast, like striking-snake fast. Lots of people who think of turtles only as slow-movers have gotten an unpleasant surprise when the neck and head projected out twice as far and ten times as fast as they expected.

    When I was about 8 years old I picked up box turtle backwards, with its head toward my palm instead of sticking out between thumb and forefinger, and it reached up and bit the meat of my hand. Its beak took out a neat little plug of skin and connective tissue about the size of a BB. That’s the only time I’ve had a turtle draw blood, but I’ve had a lot of close calls. I like feeding Easty meal worms by hand, and sometimes she misses and gets my fingertips. So far she hasn’t broken the skin, but she can bite hard.

  9. Brad Lichtenstein Says:

    Hm. Sounds like “feeding mealworms by hand” should involve slow toss. Plus, if they can grab them in-air the way dogs get frisbees, that would be an awesome video…

    I guess I still love cats, despite the massively painful bite to the wrist one gave me when I was five-ish years old. I remember screaming, the bloody vampire marks right among the tendons you see at the skin just superior to the base of the palm.

    Good to know about turtle bites. I guess I’ve always felt enough introvert empathy, to just leave them be.

  10. Alyson Brink Says:

    I love this!!

  11. kris michael Says:

    My idea was that since boxies can retract their entire bodies inside the shell and lock the door it takes up more space. Limiting neck and leg length. Or move out altogether and rent the thing to Ren and Stimpy. It also might limit size. I realize I don’t know how many types of turtle can completely retract their bodies, I think the popular notion is that all or most turtles can. It must be very few. Like armadillos.

    Side necks utilize their space more efficiently, it may not seem as elegant of a solution but it allows for longer necks. I wonder if there were side-necked sauropods? Probably didn’t need to worry about it when they could just stick their head in a hole in the ground.

    The idea of eating an animal that’s ‘too cute’. My grandma doesn’t like eating animals that are too cute or too ugly. Maybe because her father fed her a rattlesnake he shot when she was a kid. (life during the depression wasn’t easy) I show her a picture of a monkfish or fry up calamari and she doesn’t want to eat it. I guess chickens and salmon are ‘just right’.

  12. Matt Wedel Says:

    My idea was that since boxies can retract their entire bodies inside the shell and lock the door it takes up more space. Limiting neck and leg length.

    Oh, okay, yeah, that makes perfect sense. And because the plastron is hinged just once, at the midpoint, they lose a LOT of internal real estate when the drawbridge is all the way up, front and back.

    Sidenecks kinda creep me out, partly because of the inherent asymmetry in their neck-folding, partly because even folded in they have the side of the neck still exposed between carapace and plastron. Just seems risky. The tortoise solution of armoring the outside of the forelimbs and the bottoms of the feet and only pulling the head all the way in seems like a better compromise. I grew up exclusively around cryptodires, though, so the two previous sentences are entirely uninformed opinions that should probably be ignored or ridiculed.

  13. Brad Lichtenstein Says:

    I will both ignore AND ridicule your opinions. Actually, I won’t do either… Do there exist side-necked creatures? In terms of risk/vaguely similar concept, we do have the flounder. Risk to the individual isn’t that important to evolutionary success (how many sauropods live to maturity? Or turtles, for that matter), it’s whether enough individuals survive to perpetrate the line. I know everyone here knows that, it just seems an appropriate moment for Captain Obvious.


  14. Have you ever seen an obese box turtle try to close up? It’s hilariously pathetic. When they secure the front, they bulge out the back; if you then touch their exposed hindquarters, they will try to tighten up the back, thereby bulging out the front.

    A thought on box turtle size: in my experience Terrapene are often found in densely vegetated ecotones, where their small size allows them to move between plants and exploit small mammal trails that would be impassable to larger turtles. Perhaps more importantly, as temperate zone animals they must find adequate shelter for cold weather. They can’t burrow like Gopherus or nestle underwater like aquatic species, so they have to find existing crevices; the smaller the turtle, the more crevices are available to it.

  15. Matt Wedel Says:

    Brad and Nathan, you both make good points. But one correction:
    They can’t burrow like Gopherus…
    Au contraire — they can and do. Okay, box turtle burrows aren’t as long and complex as those of Gopherus, but both the T. carolina and T. ornata subspecies are known to burrow, both to make shallow burrows for day-to-day rest and shelter, and deep ones for hibernation/brumation in winter and estivation in summer (in areas where that’s hot and dry enough to be required). This is in the literature, and I’ve seen it for myself.

    I wonder if we’ve simply lost a lot of continental North American tortoises, so that box turtles and Gopherus are the last ones left standing, creating a pattern that reflects extinction more than ecology.

    Oh, and Brad: yes, there are side-necked turtles, and lots of ’em on the southern continents. An image search for ‘side-necked turtle’ or ‘pleurodire’ will turn up lots of interesting examples for you to ponder.

  16. LeeB Says:

    Pretty much everywhere that had large tortoises lost them as people spread around the world; starting with Africa a few million years ago.
    Large tortoises used to be very successful in warmer areas; they evolved multiple times in different continents from smaller species.
    So presumably the present living medium species represent a pattern reflecting extinction of the larger species but also of evolving where they were in competition with the larger extinct species and especially with their smaller offspring.


  17. I did not know that Terrapene could dig primary burrows of any significance; I thought they were limited to expanding existing root-traces and mammal burrows. Neat! It must be very laborious for them, with their tall shells and puny (relative to Gopherus anyhow) limbs.

    There is definitely a significant tortoise fossil record in North America, and they occurred much further north than Gopherus does today. At least as late as the Miocene there were tortoises, large and small, in Nebraska. There were still large tortoises in Florida in the late Pleistocene.

  18. kris michael Says:

    When I think about turtle evolution (pleurodire vs cryptodire) I have a vague memory of when I was a kid, cramming a suitcase. At the last moment I had a long, neck shaped object it took me longer then it should have to fit. It’s not surprising turtles turn up in children’s programs and fables, there’s something about their design that tickles the imagination. What IS inside that shell?

    I think they’re a good argument for evolution. Why would an intelligent creator make such a silly animal that’s so hard for other animals to crack? It’s another of endless examples of how broken humans are in the natural systems, wiping out large tortoises. Only took 250 million years for evolution to outsmart the shell. An argument for an intelligent creator, how could that not make us divine and special compared to other life forms?

    When I googled for information about turtles that can completely close their shells there were a bunch of links to answers about ‘Can sea turtles close their shells’, ‘Why don’t sea turtles completely close their shells’. The image of a sea turtle inside it’s shell sinking endlessly into the Mariana Trench crossed my mind..

  19. Mike Taylor Says:

    Alright, quick questions on those distubing freaks of nature, the cryptodires:

    1. Are individuals of a species all same-handed, or so some fold left and some right?
    2. If individuals of a species are all same-handed, are different species differently handed?
    3. Are the known instances of left-handed species evolving into right-handed or vice versa?
    4. How apparent is the handedness in the morphology of the cervical vertebrae?

  20. Brad Lichtenstein Says:

    Lol, looks like we’ve turned this into “TCPOW”, Testudine Carapace Picture Of the Week. And if this is because I was making what I thought was an obvious joke reference to your signature lay talk, I do not at all apologize. These animals are much weirder than I realized!

  21. llewelly Says:

    Mike, I find your comment confusing; your questions read like they’re about side-necked turtles – Pleurodira.

    But you said Cryptodires – which are the ones that withdraw the neck in a symmetric mode, folding it vertically.

    So – which is it?

    Either way, I am interested in the answers. But of course it’s more interesting for Pleurodires.

  22. Matt Wedel Says:

    Interesting questions re: pleurodires and handedness. I wrote to a couple of turtle researchers for answers. Will let you know what I learn.


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