Tortoises are fairly distinctive animals, and while it can occasionally be tricky to identify some by species or subspecies, it usually isn’t very hard to determine whether an animal is a tortoise or not.
In most cases, any reptile with a highly domed shell, elephantine feet, and land-dwelling habit is likely to be a tortoise. But there are a few exceptions. For example, box turtles are called “turtle,” but they appear to be tortoises in most respects.
In this article, I’ll shed some light on this regularly asked question, and explain whether or not box turtles are indeed tortoises.
Are Box Turtles Tortoises?
Simply put, no.
The term “box turtle” is the common name applied to any of five species within the genus Terrapene. By contrast, the term “tortoise” applies to approximately 49 species within the family Testudinidae.
Nevertheless, box turtles are often mistaken for and confused with tortoises.
Phenetics vs Phylogeny
Part of the reason that people confuse tortoises and box turtles is because they’re approaching animal classification from a phenetic rather than phylogenetic point of view.
Phenetics involves the classification of animals (or any other life form) based on similar visible features. For example, we’re all taught in elementary school that animals with hair or fur are mammals. But this is not true or in keeping with the current scientific approach to animal classification. After all, moths are often covered in hair, but they’re not even vertebrates, let alone mammals.
Accordingly, modern scientists eschew the phenetic approach in favor of something called phylogeny.
Phylogeny is also a manner of classifying animals, but it does so based on shared evolutionary history. In other words, two animals that have the same ancestor are considered to be related, regardless of what they look like. Using our previous example, we can tell that even though a moth and koala are both covered in fur, they are not very closely related at all. One is an insect, while the other is a mammal.
The Turtle Family Tree
We can now turn our attention back to the subject of box turtles and tortoises.
Both groups of animals are members of the class Reptilia, so they are reptiles, just like snakes and lizards (among others). Additionally, both groups are in the order Testudines, a group which includes all living turtles. This is why you could rightly apply the term turtle to any turtle or tortoise species, though you cannot do the opposite. All tortoises are turtles, but only one group of turtles contains tortoises.
Moving down another layer of classification, both groups are placed within the suborder Cryptodira, which includes all turtles whose necks retract vertically, rather than to the side. However, once we arrive at the family level, the two groups diverge. Tortoises are members of the family Emydidae, while tortoises are in another group, the family Testudinidae.
Common Names vs Scientific Names
Another important thing to understand is that there is a difference between common names and scientific names.
Common names are those used by laypersons when referring to animals. For example, terms like “eastern box turtle,” “red-footed tortoise,” and “human” are all common names. But common names aren’t governed by any type of authority; they’re simply the names ordinary people apply to different animals.
In fact, many animals have multiple common names.
For example, lady bugs are also called ladybirds, while vultures are also called buzzards. Similarly, some people call box turtles box tortoises. Often, common names differ geographically. For example, water turtles of any kind are often called terrapins by people in the mid-Atlantic region. Similarly, monitor lizards are often called goannas in Australia.
All of this means that there are no rules when using common names. You can call a box turtle a box tortoise if you like.
By contrast, scientific names (often incorrectly referred to as Latin names) are governed by an authority – The International Code of Zoological Nomenclature. These names are designed to precisely identify a given species, and they’re used consistently all over the world.
This not only allows two scientists (or zookeepers or other animal-care professionals) to know they’re referring to the same species, but it allows them to do so even if they speak different languages.
So, instead of saying “eastern box turtle,” “red-footed tortoise,” or “human,” a scientist would say Terrapene carolina, Chelonoidis carbonarius, or Homo sapiens.
Scientific names always have at least two words, which provides an important benefit – they provide some information about the animal’s relatives and evolutionary history. The first word refers to the animal’s genus, while the second word refers to the animal’s species.
As an example, we could see that eastern box turtles (Terrapene carolina) are not in the same genus as red-footed tortoises (Chelonoidis carbonarius). However, yellow-footed tortoises (Chelonoidis denticulatus) are in the same genus as red-footed tortoises. This means that they’re relatively closely related.
Box Turtles vs Tortoises: Differences Relevant to Keepers
Technical distinctions and complicated classification systems aside, box turtles and tortoises are remarkably similar animals. And from a keeper’s perspective, box turtles and tortoises require relatively similar care:
- Both box turtles and tortoises will thrive best in an enclosure that is primarily comprised of dry ground. Both require drinking water, but many box turtles will appreciate a more substantial water section that’s large enough to permit soaking.
- Box turtles and tortoises both require proper temperature and humidity levels to thrive. The preferred temperature range of box turtles is lower than the preferred range of many tortoises, but this varies a bit based on the species of box turtle and tortoise in question.
- Both box turtles and tortoises require full-spectrum lighting that provides light in the UVA an UVB portion of the spectrum.
- Both box turtles and tortoises will require places in which they may hide, and most will appreciate a substrate that permits digging and burrow formation.
The largest difference between box turtles and tortoises is that box turtles are typically omnivorous and consume insects and small vertebrates, while most tortoises are almost exclusively herbivorous (though there are some exceptions).
Other Important Distinctions
There is one more difference between box turtles and tortoises that is important to note: Box turtles have hinged shells. Specifically, they have hinged plastrons. This means that once they’ve withdrawn their heads, tails, and legs inside their shells, they can then “close” the shell, somewhat like you’d close a box (hence their common name).
Tortoises cannot do this. Tortoises have rigid plastrons, which lack a hinge. However, the members of one tortoise genus – Kinixys, commonly called hinge-back tortoises – do have hinged shells. But in these tortoises, the hinge is located on the carapace, rather than the plastron.
Interestingly, these hinged shells reflect another trait that hinge-back tortoises have with box turtles; unlike most tortoises, who are largely herbivorous, hinge-back tortoises are more omnivorous and consume insects and other prey from time to time.
If you’ve enjoyed this article, here’s a link to How Fast Can a Tortoise Run? that you may also enjoy.
Citations
- University College London – Testudines
- National Zoo – Eastern Box Turtle
- International Code of Zoological Nomenclature – The Code Online
