Just having a shell doesn’t explain the long-term success of the turtle and the tortoise, although it certainly sets them apart. As an order, called Testudinata or Testudines, they’re fascinating.
They live on every continent except Antarctica, survive in a wide variety of extreme environments, and eat unthinkable diets. Plus they’ve been doing it for longer than we’ve been around as a species.
10 They Dig Rain Basins
Many species of tortoise thrive in some of the hottest deserts in the world. They escape from extreme temperatures, over 60 degrees Celsius (140 °F), by burrowing deep underground. With heat keeping them from exploring their already water-scarce environment, they have to be skilled at conservation to avoid shriveling up and dying.
Desert tortoises tackle the problem by efficiently absorbing water from plants and by reabsorbing water that most species would pass as liquid waste. However, the most striking way that the tortoise keeps himself hydrated is by digging rain basins.
Tortoises are crepuscular, which means they are awake and active when temperatures are right, usually at dawn or dusk. While marching about the desert at his preferred time of day, the thirsty tortoise stops to dig a small pool, which will fill in the next time it rains. He remembers where his puddles are and returns to drink after the next storm passes.
9 They Make Gardens
Water collection is something the tortoise sets out to do, but these desert dwellers are also accidental gardeners. In her foraging, the desert tortoise finds and consumes a variety of plants: cacti, herbs, and shrubs. She doesn’t stop with just a nibble, either; she eats the entire plant, right down to the ground.
The desert derives benefits from the tortoise stripping these plants bare because tortoises poop a lot. Eating entire plants means eating a wide variety of seeds. The tortoise brings back, deposits, fertilizes, and plants her favorite foods all around her burrow. She transplants the widespread desert life into a single location.
Gradually, her existence creates and maintains a scrubland niche which sustains her and other life within the desert. With her long life span, a well-established tortoise provides much-needed balance in the unforgiving environment of her desert home.
8 They Eat Poison And Glass
Not content with just greens, some turtles dine exclusively on food that kills just about everything else that takes a bite. The hawksbill sea turtle is a specialized spongivore, meaning she primarily eats creatures that contain or produce poisons and toxins.
Hawksbills have enough of these toxic compounds in their bodies that people occasionally die from secondary poisoning after eating the turtle’s meat. If that’s not enough, sponge skeletons are made up of silica spicules, essentially just shards of glass.
The hawksbill doesn’t appear to have a way of breaking down these shards or otherwise causing them to become harmless. They just seem to eat them and not be bothered by the consequences. Scientists have examined dead hawksbills who have bellies full of sharp glass, much of which is embedded in their digestive tract. Although we’re not sure how, these sea turtles continue to munch on their unforgiving food without any apparent negative side effects.
7 They Lure Prey
With its hooked beak, strong claws, and weight of up to 90 kilograms (200 lb), the alligator snapping turtle has inspired a mythos of bite stories around her species. Although the alligator snapper does bite readily in defense, a 2002 study suggests that her bite isn’t all that impressive.
Someone on the receiving end of such a bite would probably disagree, but bite pressure tests show that her bite power is dwarfed by some other turtle species and is even less than the human bite range. However, she takes home first prize in luring prey.
The alligator snapper’s tongue has a wormlike appendage, which she wiggles to attract nearby fish. Resting at the bottom of a stream with her mouth open wide and deceptive tongue floating, the alligator snapper doesn’t need the hardest bite. She just needs to be patient and quick.
6 They Inflate Their Bodies
To be globally successful, turtles and tortoises also have to keep from being eaten. At first, we might think that their shells have this covered, but they don’t always provide as much protection as it seems.
Desert tortoises can pull their heads back into their bodies and shield themselves with their front feet, but motivated birds can still peck around their defenses. This predation causes many deaths among juvenile tortoises.
The pancake tortoise steps up the shell game by living in crevices among rocky outcrops. His flat body and shell allow him to move into spaces unavailable to others of his kind and to spend most of his life hiding.
When threatened, this tortoise is able to puff up his body by expanding his lungs, making him difficult to extract. His technique works fairly well against natural predators, but his biggest threat is being so interesting that he’s snatched up for the pet trade.
5 They Stink Like Skunks
When not making herself a nuisance by ganging up to steal bait or catch and eat baby ducks, the African helmeted turtle digs into the mud of the south Sahara to nest and hide. She doesn’t have any way of preventing someone from hauling her up again, except to make that person wish they hadn’t bothered.
Not only does she yield little meat, but the helmeted turtle also produces a foul-smelling liquid from glands behind her flippers and under her chin when she’s stressed. Overloading her predators with the lingering smell of feces can make her a lot less appetizing, and other animals are smart enough not to stick around.
People persist in catching the creatures, though, both for eating and the pet trade. Helmeted turtles are cute, and their faces look like they’re smiling. So that must be enough for some people to put up with a little stench.
4 They Are Sensitive Acrobats
We tend to associate the deliberate movements of a tortoise with sloth or lack of coordination. In fact, the tortoise is a particularly skilled digger and climber due to his excellent sense of balance.
There are many other myths about how tortoises perceive the world. One pervasive belief about the tortoise’s shell is that it is disconnected from him and he cannot use it to feel. This has led to some terrible experiments. More recent studies show that he is sensitive on all parts of his body, including the shell.
The tortoise’s greatest strength is his sense of smell, which guides him through most daily activities: finding food, finding a mate, and steering clear of anything that’s hungry. Our friend’s hearing is not attuned to higher-frequency sounds, and his vision is probably focused on movement. But his senses are still more powerful than common misconceptions would have us believe.
3 They Breathe Without A Diaphragm
With her internal organs sandwiched between the two halves of her shell, the carapace on top and the plastron on the bottom, most turtles don’t have any room to expand a diaphragm or rib cage to breathe. Instead, she has to rely on other muscle groups to draw air into her lungs.
To do this, she makes specific movements with her flippers, with her neck muscles, and sometimes with smaller, internal muscles near her lungs. Depending on her species, she may also use a method of drawing oxygen from the water, called buccopharyngeal breathing, which requires her to suck in water through her mouth and blow it out her nose.
The downside of both of these methods is that they require a lot of energy. When conserving their energy or for those that cannot use buccopharyngeal breathing, the turtles have another trick for getting oxygen when underwater.
2 They Breathe Through Their Butts
Turtles and tortoises all have a cloaca, a single vent for all their reproductive and waste disposal needs. They poop and lay eggs (or extend their phallus) through the same opening. Surprisingly, some turtles also use their cloaca to breathe.
The Fitzroy River turtle is especially well-known for this trick. By drawing water into sacs within his cloaca, he can stay underwater for so long that few people in his native Australia realize that he exists. The inside of his cloacal sacs are similar to gills, allowing him to efficiently draw oxygen from the water.
It isn’t perfect, though. Eventually, he has to surface for air, but cloacal breathing means he can stay submerged for up to a week. This is an especially effective method for hiding from his predators.
1 They’ve Had It Right A Long Time
Scientists have found fully shelled turtle fossils dating back 120 million years. Some believe this could be an ancestor of modern-day turtles, while others argue that multiple groups of organisms have evolved this shape and structure to adapt to land or sea.
Either way, this history speaks to the success of the turtle shape. As full shells were developed, a few other changes were made from their reptile ancestors. Turtles used to have teeth, and they weren’t always able to draw in their necks.
Over time, they realized that beaks worked just fine and that hiding inside their armor might make them a little safer. Somewhere around 120 million years ago, Testudinata settled on their modern shape. Since then, they’ve made some fascinating tweaks and continue to be a truly impressive order.
Ben is an elementary schoolteacher, an avid reader, a hobby beekeeper, and an amateur grower of orchids. He is fascinated by reptiles, and he owns three, which is entirely too few for him and entirely too many for his best girl. He writes because Word does not get tired of him prattling on about any of his current obsessions (or at least it hasn’t yet complained).