10 Colorful Facts About Chameleons


You probably know that these lizards can change their skin color, but they’ve got plenty of other special tricks as well. In fact, they might be the world’s most talented reptiles. Chameleons can shoot out their tongues at alarming speeds, use their tails as extra limbs, and even see in two different directions at once. Impressive, no?


Most lizards have fairly unremarkable feet. In the majority of species, they're comprised of four to five toes that can move independently of each other—just as ours do. But evolution has taken chameleon limbs in a very different direction. A chameleon’s foot consists of two fleshy pads that oppose each other. One pad contains three digits that are fused together while the other has two fused digits.

Up in the tree canopies where they live, these feet come in handy. Like a set of pincers, the opposing pads on each foot firmly clamp down onto vines and branches. Also, whereas most lizards have sprawling limbs, chameleons usually hold their legs almost directly underneath their bodies. This gives them an athletic gait for a modern reptile—walking this way keeps the center of gravity directly above the feet, which helps the animals stay balanced.


Currently, there are around 200 different chameleon species, 44 percent of which can be found on Madagascar—leading some experts to wonder if the whole chameleon family originally evolved there (although a modern analysis deemed mainland Africa a more likely origin point). Elsewhere in the world, some members of this incredible group occur naturally in India, Asia minor, southern Europe, and mainland Africa.



In 2012, researchers discovered a new species of chameleon that—as of this writing—is the smallest on record. Known as Brookesia micra, the diminutive animal dwells on Nosy Hara, an islet off the coast of Madagascar. The diurnal lizard’s maximum adult length is only an inch, and juveniles can fit on the head of a match. (Sure, it's a cliche, but ... really. They can.) Meanwhile, mainland Madagascar is home to the two largest chameleons on record: the Oustalet’s chameleon and the Parson’s chameleon, each of which can grow up to 27 inches.


Contrary to popular belief, when a chameleon changes its skin color, the animal usually isn’t trying to camouflage itself by blending into the environment. More often, this remarkable ability is used as a way of controlling its body temperature. By lightening their skin, chameleons can cool themselves down, since lighter colors are better at reflecting the sun’s rays. On the other hand, adopting a dark complexion is a good way to warm up when it gets chilly outside.

Another primary function of color change is communication: Altering skin tone can let potential mates or rivals know what’s on your mind. For example, a female common chameleon (Chamaeleo chamaeleon) displays bright yellow spots when she’s ready to mate. Afterwards, she’ll darken her skin tone and show off blue and yellow spots to inform nearby males to stay away. (Angry hisses also help get the point across.)

Males, too, wear their emotions on their skin. When two bull graceful chameleons (Chamaeleo gracilis) cross paths, their skins become paler and more heavily spotted. Faced with the same situation, a pair of male warty chameleons (Furcifer verrucosus) will turn bright blue and green—but only on the lower half of their bodies.

When such displays aren’t enough, many males won’t shy away from physical confrontation. Amazingly, it looks like variations in skin color might predict the outcome of these squabbles before they happen. In 2013, Russell Ligon and Kevin McGraw of Arizona State University monitored 45 encounters between captive veiled chameleons (Chamaeleo calyptratus—pictured above). Before engaging with each other, males of this species show off the vibrant stripes on their sides. Both lizards intentionally brighten these up as a way to demonstrate their health while also making themselves look bigger. Ligon and McGraw discovered that—in most cases—any resulting fight was won by whichever combatant had brighter and more rapidly-changing stripes.



Until recently, scientists thought that the reptiles changed color by manipulating the pigments inside their skin cells. But it's much more complicated. In 2015, scientists at the University of Geneva took a close look at the skin of the male panther chameleon (Furcifer pardalis) and discovered two layers of specialized cells lying under the creature’s hide that were loaded with tiny nanocrystals—the key to a chameleon’s color-changing prowess.

The name of the game is reflection. When a male panther chameleon is relaxed, the cells containing its crystals are held closely together. In this position, they reflect blue light, which—when filtered through yellow skin pigments—makes the animal look green. Somehow, chameleons can expand and reduce the distance between those nanocrystals. By spreading them farther apart, the reptiles cause their crystals to reflect yellow or red light. The skin’s apparent color then changes accordingly.


Most chameleons have long, grasping tails that basically function like a fifth limb. In the majority of species, it can support the animal’s entire bodyweight, allowing a chameleon to move between branches more easily. One thing that the appendage cannot do, however, is automatically break off when a predator grabs it, as the tails of anoles, leopard geckos, and many other lizards do—if a chameleon’s tail is severed, it won’t grow a replacement.


Each eye has the incredible range of motion of 90 degrees vertically and 180 degrees horizontally. And that’s not all: The peepers can also move in opposite directions—so while one eye is looking upwards and to the left, the other might simultaneously wander downwards and to the right. This allows a chameleon to scan most of the surrounding area for food without even moving its head. If one wandering eye should spy a tasty insect, the other one will move over and fixate on the target as well, giving the lizard some depth perception.


After a chameleon gets both eyes locked onto its prey, a high-speed weapon is deployed: the reptile’s ultra-sticky tongue, which can be 2.5 times as long as its body and can be deployed and reeled back in in less than a second.

Recently, biologist Christopher Anderson used a high-speed camera to record 55 different chameleons—representing 20 species—as they snapped up prey. Anderson noted that the speed and relative force of a chameleon’s tongue seems to be inversely proportional to the creature’s overall size. In other words, it looks like smaller species can fire their tongues more rapidly and more powerfully than their bigger cousins do. The tiniest species that Anderson examined was Rhampholeon spinosus, which fired off its tongue at 8500 feet per second. Meanwhile, the biggest lizard of the bunch—a 2-foot-long Oustalet’s chameleon—had a peak tongue acceleration rate that was 18 percent slower.


How does a chameleon’s tongue hold onto the insects and small vertebrates it touches? With spit that's 400 times more viscous than that of a human being. This ultra-sticky substance coats the tongue, giving the lizards an edge that helps them pull even heavy victims into their jaws.


These lizards are known to sway back and forth—sometimes erratically—while walking. If there’s a method to this madness, scientists have yet to identify it. Many speculate that the weird behavior helps chameleons imitate swaying tree leaves, thus further camouflaging themselves. However, so far, no one’s been able to prove this hypothesis.

Penn Vet Working Dog Center
Stones, Bones, and Wrecks
New Program Trains Dogs to Sniff Out Art Smugglers
Penn Vet Working Dog Center
Penn Vet Working Dog Center

Soon, the dogs you see sniffing out contraband at airports may not be searching for drugs or smuggled Spanish ham. They might be looking for stolen treasures.

K-9 Artifact Finders, a new collaboration between New Hampshire-based cultural heritage law firm Red Arch and the University of Pennsylvania, is training dogs to root out stolen antiquities looted from archaeological sites and museums. The dogs would be stopping them at borders before the items can be sold elsewhere on the black market.

The illegal antiquities trade nets more than $3 billion per year around the world, and trafficking hits countries dealing with ongoing conflict, like Syria and Iraq today, particularly hard. By one estimate, around half a million artifacts were stolen from museums and archaeological sites throughout Iraq between 2003 and 2005 alone. (Famously, the craft-supply chain Hobby Lobby was fined $3 million in 2017 for buying thousands of ancient artifacts looted from Iraq.) In Syria, the Islamic State has been known to loot and sell ancient artifacts including statues, jewelry, and art to fund its operations.

But the problem spans across the world. Between 2007 and 2016, U.S. Customs and Border Control discovered more than 7800 cultural artifacts in the U.S. looted from 30 different countries.

A yellow Lab sniffs a metal cage designed to train dogs on scent detection.
Penn Vet Working Dog Center

K-9 Artifact Finders is the brainchild of Rick St. Hilaire, the executive director of Red Arch. His non-profit firm researches cultural heritage property law and preservation policy, including studying archaeological site looting and antiquities trafficking. Back in 2015, St. Hilaire was reading an article about a working dog trained to sniff out electronics that was able to find USB drives, SD cards, and other data storage devices. He wondered, if dogs could be trained to identify the scents of inorganic materials that make up electronics, could they be trained to sniff out ancient pottery?

To find out, St. Hilaire tells Mental Floss, he contacted the Penn Vet Working Dog Center, a research and training center for detection dogs. In December 2017, Red Arch, the Working Dog Center, and the Penn Museum (which is providing the artifacts to train the dogs) launched K-9 Artifact Finders, and in late January 2018, the five dogs selected for the project began their training, starting with learning the distinct smell of ancient pottery.

“Our theory is, it is a porous material that’s going to have a lot more odor than, say, a metal,” says Cindy Otto, the executive director of the Penn Vet Working Dog Center and the project’s principal investigator.

As you might imagine, museum curators may not be keen on exposing fragile ancient materials to four Labrador retrievers and a German shepherd, and the Working Dog Center didn’t want to take any risks with the Penn Museum’s priceless artifacts. So instead of letting the dogs have free rein to sniff the materials themselves, the project is using cotton balls. The researchers seal the artifacts (broken shards of Syrian pottery) in airtight bags with a cotton ball for 72 hours, then ask the dogs to find the cotton balls in the lab. They’re being trained to disregard the smell of the cotton ball itself, the smell of the bag it was stored in, and ideally, the smell of modern-day pottery, eventually being able to zero in on the smell that distinguishes ancient pottery specifically.

A dog looks out over the metal "pinhweel" training mechanism.
Penn Vet Working Dog Center

“The dogs are responding well,” Otto tells Mental Floss, explaining that the training program is at the stage of "exposing them to the odor and having them recognize it.”

The dogs involved in the project were chosen for their calm-but-curious demeanors and sensitive noses (one also works as a drug-detection dog when she’s not training on pottery). They had to be motivated enough to want to hunt down the cotton balls, but not aggressive or easily distracted.

Right now, the dogs train three days a week, and will continue to work on their pottery-detection skills for the first stage of the project, which the researchers expect will last for the next nine months. Depending on how the first phase of the training goes, the researchers hope to be able to then take the dogs out into the field to see if they can find the odor of ancient pottery in real-life situations, like in suitcases, rather than in a laboratory setting. Eventually, they also hope to train the dogs on other types of objects, and perhaps even pinpoint the chemical signatures that make artifacts smell distinct.

Pottery-sniffing dogs won’t be showing up at airport customs or on shipping docks soon, but one day, they could be as common as drug-sniffing canines. If dogs can detect low blood sugar or find a tiny USB drive hidden in a house, surely they can figure out if you’re smuggling a sculpture made thousands of years ago in your suitcase.

15 Confusing Plant and Animal Misnomers

People have always given names to the plants and animals around us. But as our study of the natural world has developed, we've realized that many of these names are wildly inaccurate. In fact, they often have less to say about nature than about the people who did the naming. Here’s a batch of these befuddling names.


There are two problems with this bird’s name. First, the common nighthawk doesn’t fly at night—it’s active at dawn and dusk. Second, it’s not a hawk. Native to North and South America, it belongs to a group of birds with an even stranger name: Goatsuckers. People used to think that these birds flew into barns at night and drank from the teats of goats. (In fact, they eat insects.)


It’s not a moss—it’s a red alga that lives along the rocky shores of the northern Atlantic Ocean. Irish moss and other red algae give us carrageenan, a cheap food thickener that you may have eaten in gummy candies, soy milk, ice cream, veggie hot dogs, and more.


Native to North America, the fisher-cat isn’t a cat at all: It’s a cousin of the weasel. It also doesn’t fish. Nobody’s sure where the fisher cat’s name came from. One possibility is that early naturalists confused it with the sea mink, a similar-looking creature that was an expert fisher. But the fisher-cat prefers to eat land animals. In fact, it’s one of the few creatures that can tackle a porcupine.


American blue-eyed grass doesn’t have eyes (which is good, because that would be super creepy). Its blue “eyes” are flowers that peek up at you from a meadow. It’s also not a grass—it’s a member of the iris family.


The mudpuppy isn’t a cute, fluffy puppy that scampered into some mud. It’s a big, mucus-covered salamander that spends all of its life underwater. (It’s still adorable, though.) The mudpuppy isn’t the only aquatic salamander with a weird name—there are many more, including the greater siren, the Alabama waterdog, and the world’s most metal amphibian, the hellbender.


This weird creature has other fantastic and inaccurate names: brick seamoth, long-tailed dragonfish, and more. It’s really just a cool-looking fish. Found in the waters off of Asia, it has wing-like fins, and spends its time on the muddy seafloor.


The naval shipworm is not a worm. It’s something much, much weirder: a kind of clam with a long, wormlike body that doesn’t fit in its tiny shell. It uses this modified shell to dig into wood, which it eats. The naval shipworm, and other shipworms, burrow through all sorts of submerged wood—including wooden ships.


These leggy creatures are not spiders; they’re in a separate scientific family. They also don’t whip anything. Whip spiders have two long legs that look whip-like, but that are used as sense organs—sort of like an insect’s antennae. Despite their intimidating appearance, whip spiders are harmless to humans.


A photograph of a velvet ant
Craig Pemberton, Wikimedia Commons // CC BY-SA 3.0

There are thousands of species of velvet ants … and all are wasps, not ants. These insects have a fuzzy, velvety look. Don’t pat them, though—velvet ants aren’t aggressive, but the females pack a powerful sting.


The slow worm is not a worm. It’s a legless reptile that lives in parts of Europe and Asia. Though it looks like a snake, it became legless through a totally separate evolutionary path from the one snakes took. It has many traits in common with lizards, such as eyelids and external ear holes.


This beautiful tree from Madagascar has been planted in tropical gardens all around the world. It’s not actually a palm, but belongs to a family that includes the bird of paradise flower. In its native home, the traveler’s palm reproduces with the help of lemurs that guzzle its nectar and spread pollen from tree to tree.


Drawing of a vampire squid
Carl Chun, Wikimedia Commons // Public Domain

This deep-sea critter isn’t a squid. It’s the only surviving member of a scientific order that has characteristics of both octopuses and squids. And don’t let the word “vampire” scare you; it only eats bits of falling marine debris (dead stuff, poop, and so on), and it’s only about 11 inches long.


Early botanists thought that these two ferns belonged to the same species. They figured that the male fern was the male of the species because of its coarse appearance. The lady fern, on the other hand, has lacy fronds and seemed more ladylike. Gender stereotypes aside, male and lady Ferns belong to entirely separate species, and almost all ferns can make both male and female reproductive cells. If ferns start looking manly or womanly to you, maybe you should take a break from botany.


You will never find a single Tennessee warbler nest in Tennessee. This bird breeds mostly in Canada, and spends the winter in Mexico and more southern places. But early ornithologist Alexander Wilson shot one in 1811 in Tennessee during its migration, and the name stuck.


Though it’s found across much of Canada, this spiky plant comes from Europe and Asia. Early European settlers brought Canada thistle seeds to the New World, possibly as accidental hitchhikers in grain shipments. A tough weed, the plant soon spread across the continent, taking root in fields and pushing aside crops. So why does it have this inaccurate name? Americans may have been looking for someone to blame for this plant—so they blamed Canada.

A version of this story originally ran in 2015.


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