Tag Archives: camouflage

This plant evolved camouflage to hide from humans

Fritillaria delavayi is easily recognized thanks to its green leaves and yellow flowers (left). But recently, the plant changed its color to gray, brown-red, and teal in order to camouflage and avoid harvesting by humans.

Most are aware of animal camouflage, where both prey and predator employ various disguises to blend with their environment and avoid attracting attention. However, the same evolutionary pressures that lead some animals to develop camouflage as a defense mechanism are also acting upon other living things, such as plants. Strangely enough, a new study documents how a perennial herb growing in China has evolved camouflage in order to avoid harvesting by human hands.

Plants vs humans

Humans have been deliberately breeding plants since at least the agricultural revolution more than 8,000 years ago. However, we’re far less used to seeing plants evolve in response to human activity without our conscious interference.

For years, Yang Niu, a scientist at the Kunming Institute of Botany at the Chinese Academy of Sciences, has been documenting the fascinating world of plant camouflage. In 2018, he and colleagues in China and the UK published a review concluding that many plants use a host of camouflage techniques long known to be used by animals.

These include blending with the background, “disruptive coloration” (using high-contrast markings to break up the perceived shape of an object), and “masquerade” (looking like an unimportant object predators might ignore, such as a stone).

This makes sense. If plants evolved lush coloring to entice pollinators or enhance photosynthesis, there’s no reason why traits that also offer protection wouldn’t also be favored in some situations.

One prime example is Corydalis hemidicentra, a plant whose leaves match the colour of rocks where it grows. What’s more, different populations of this species look different in different places.

Credit: Yang Niu.

Now, in a new study, Niu and colleagues have documented a new species that employs camouflage — but unlike other plants, this may be the first species to our knowledge that employs camouflage to avoid human predators.

Fritillaria delavayi, a plant that grows in the mountain regions of China, has been harvested by humans for medicinal purposes for at least 2,000 years. They always had green leaves and bell-shaped yellow flowers until recently when many plants colored brown or teal, matching the backdrop of their environment, have been noticed.

Writing in the journal Current Biology, Niu and colleagues say that the plants have evolved camouflage in order to avoid harvesting. It takes around 3,500 flowers to produce a single pound of medicinal product, which can cost up to $218. In rural China, where economic prospects are scarce, the demand for the herb has driven heavy harvesting — and the plants have wised up in response.

“Like other camouflaged plants we have studied, we thought the evolution of camouflage of this fritillary had been driven by herbivores, but we didn’t find such animals,” Niu, co-author of the study, said in a statement. “Then we realized humans could be the reason.”

Using a spectrometer, the researchers recorded how closely the color of the plants matched their environment. Plants from multiple locations were analyzed. The team also kept records of the annual weight of bulbs harvested from 2014 to 2019, which showed where Fritillaria was harvested heavily in each area.

Fritillaria delavayi in an area with low harvesting. Credit: Yang Niu.

Remarkably, the regions with the most intense harvesting also had plants with the most effective camouflage patterns that mimicked their backdrop. Meanwhile, Fritillaria plants that were largely left alone grew green as they have for thousands of years.

“It’s remarkable to see how humans can have such a direct and dramatic impact on the coloration of wild organisms, not just on their survival but on their evolution itself,” said Martin Stevens, an ecologist at the University of Exeter and co-author of the study, in the statement.

“Many plants seem to use camouflage to hide from herbivores that may eat them—but here we see camouflage evolving in response to human collectors. It’s possible that humans have driven evolution of defensive strategies in other plant species, but surprisingly little research has examined this.”

Humans have been selecting crops, animals, and years for so much time that it’s fascinating to hear about unintentional selection for a change. There may be many other examples of this that scientists have yet to learn about.

Deaf moths use acoustic camouflage to escape bats

A new study has found that moths have developed a remarkable type of camouflage — it’s acoustic rather than visual.

This image shows a Madagascar bullseye (Antherina suraka), one of the moth species used in Thomas Neil’s research. Image credits: Thomas Neil.

When we think of camouflage, we picture a visual image — something that blends in with the surroundings. That’s because when most creatures are hiding, they want to be out of sight. But if you were hiding from a bat, for instance, that wouldn’t make much sense: bats don’t “see” with their eyes, but rather with their distinct echolocation ability (think of it like a biological sonar). So to hide from a bat, you’d need a different mechanism.

That’s what some moths figured out a long time ago.

Moths are a mainstay on bats’ menu and, naturally, they’d like to avoid being eaten. So in response, some moths have developed ears that detect the ultrasonic calls of bats, but others have remained deaf — and seemingly helpless. But that’s not quite true: a new study has revealed that these insects developed a type of “stealth coating” that serves as acoustic camouflage to evade hungry bats.

Thomas Neil, from the University of Bristol, UK explains how the fur on a moth’s thorax and wing joints provide acoustic stealth by reducing the echoes of these body parts from bat calls.

“Thoracic fur provides substantial acoustic stealth at all ecologically relevant ultrasonic frequencies,” said Neil, a researcher at Bristol University. “The thorax fur of moths acts as a lightweight porous sound absorber, facilitating acoustic camouflage and offering a significant survival advantage against bats.” Removing the fur from the moth’s thorax increased its detection risk by as much as 38 percent.

Neil used acoustic tomography to quantify echo strength of two deaf moth species subjected to bat predation and two butterfly species that are not. He was able to show that acoustic camouflage appears in both moth species, but is absent in the butterflies.

“We found that the fur on moths was both thicker and denser than that of the butterflies, and these parameters seem to be linked with the absorptive performance of their respective furs,” Neil said. “The thorax fur of the moths was able to absorb up to 85 percent of the impinging sound energy. The maximum absorption we found in butterflies was just 20 percent.”

A rotating 3D image of a moth scale. This type of structure is responsible for the acoustic camouflage. Credits: Thomas Neil.

It’s not clear when this mechanism would have emerged. The hairs on the thorax are basically just elongated scales (as you find on the wing), which emerged around 200 million years ago, long before bats evolved (65 million years ago), Neil told me in an email. It’s very hard to say whether the emergence of bats made the moths become hairier.

But what does seem clear is that bats and moths are in a sort of arms race — as the moths develop their camouflage structure, bats try to overcome it — but it’s not that easy.

“Whereas some bats have shifted the frequency of their calls to try and hide from moths that have developed hearing, shifting the frequency to try and overcome the acoustic camouflage of moths would not work,” Neil told ZME Science.

“This is because the absorption is broadband, with the effect being consistent over the frequencies that we measured (20 -160 kHz, the range which most bats use). One thing bats could do would be to simply emit louder echolocation calls to try and get stronger echoes back from the moth, but we have not done any field testing yet to see if this is the case.”

Further research will try to establish how common this occurrence is, and whether there is a difference between deaf and non-deaf moths. There’s no reason why stealth coating and the ability to hear are mutually exclusive; although deaf moths have more evolutionary pressure on them to evolve this type of ability, it would still be a benefit for them to be able to camouflage acoustically, Neil adds.

“We only tested two moths in this study from the family Saturniidae (Antherina suraka and Callosamia promethea). The study is a sort of a proof of concept, we’ve shown that the fur on the thorax can absorb ultrasound, but the extent to which it is present amongst the many moth species is currently unknown.”

“We’re currently working on quantifying to ‘furriness’ of moths across different families to see if there is any relationship between the different forms of defence against bats, he concludes”.

Neil will describe his work during the Acoustical Society of America’s 176th Meeting.

Bluetongue.

Australian skinks will literally stick their tongues out at predators — and it works!

When in doubt, stick your tongue out at them!

Bluetongue.

“You asked for it punk!”
Image credits Shane Black.

Skinks in the genus Tiliqua are pretty inconspicuous as far as lizards go. They don’t really like to draw attention to themselves, and they’re decidedly lizard-shaped. New research shows that when their unassuming nature fails to garner the peace of mind they desire (from predators), the skinks fall back to a surprising — and surprisingly effective — last-ditch defense: their tongues.

Their what now?

Bluetongued skinks are fairly widely spread throughout Australia, eastern Indonesia, and Papua New Guinea. They’re omnivorous, mediumly-sized lizards that primarily rely on their camouflage to keep out of sight. When under attack by a determined predator, however, they make an effort to stand out: the skinks open their mouth suddenly, as wide as they can, to reveal a brightly-colored blue tongue. Not to make them self-conscious but these tongues must be a sight to recoil from — because that’s exactly what predators do.

The behavior is used as a last line of defense to protect the skinks from attack, writes Martin Whiting, the study’s corresponding author, in a press release. The research revealed that the tongues are very reflective in the UV spectrum, and that they are more UV-luminous towards the back. Some of the lizards’ main predators, such as birds, snakes, or monitor lizards, are thought to be able to see UV light, suggesting the skinks might use this light to startle predators into breaking off their attack.

The study focused on the northern bluetongue skink (Tiliqua scincoides intermedia), the largest species of the group. The species sports good camouflage: broad brown bands across their backs to blend them into their surroundings. However, some of its main predators can still spot them, likely due to their ability to perceive UV light — so the team aimed to determine what tactics it uses to deter attackers.

First, they used a portable spectrophotometer to measure the color and intensity across different areas of the tongues of 13 skinks. This revealed that the blue tongues actually reflect UV light. Further data crunching in the lab later revealed that the tongues were almost twice as bright at the rear compared to the tip.

Mean spectra of different regions of the tongue. Associated illustration by Courtney Walcott of a Bluetongue skink performing a full-tongue display.
Image credits A. Badiane et al., 2018, Behavioral Ecology and Sociobiology.

Bloo!

The next part of the study was to identify how this bright tongue benefited the skinks. The team observed that skinks in the wild would open their mouths and stick their tongues out at would-be attackers. To find out more, the team simulated attacks on the lizards using models of their natural predators — the team used a snake, a bird, a goanna (monitor lizard), a fox — and a piece of wood as a control.

Skinks will rely on concealment for as long as they possibly can, the team reports. Should this fail, however, the lizards open their mouths widely at the last moment, revealing their UV-reflective tongues. One particularly amusing paragraph of the study suggests that the more intense attacks elicited a stronger tongue-response: the more risk the skinks felt exposed to, the more tongue they would poke at their enemies. I can relate to their fighting style.

Bluetongue display.

Northern Bluetongue skink performing a ‘full-tongue’ display in response to a simulated attack by a model predator. The face of a true warrior.
Image credits Peter Street / A. Badiane et al., 2018, Behavioral Ecology and Sociobiology.

“The lizards restrict the use of full-tongue displays to the final stages of a predation sequence when they are most at risk, and do so in concert with aggressive defensive behaviours that amplify the display, such as hissing or inflating their bodies,” explains lead author Arnaud Badiane.

“This type of display might be particularly effective against aerial predators, for which an interrupted attack would not be easily resumed due to loss of inertia.”

Finally, the team notes that tongue-displays were most often triggered by the fake bird and fox models, rather than by those of snakes or monitor lizards.

“The timing of their tongue display is crucial,” adds Badiane. “If performed too early, a display may break the lizard’s camouflage and attract unwanted attention by predators and increase predation risk. If performed too late, it may not deter predators.”

If you’re ever caught between a rock and a hard knuckle, stick your tongue out. It likely won’t be as effective as those of the skinks, but maybe you’ll confuse people enough to make your (brave and honorable) escape. Worth a shot.

The paper “Why blue tongue? A potential UV-based deimatic display in a lizard” has been published in the journal Behavioral Ecology and Sociobiology.

Researchers develop octopus skin-inspired infrared camouflage

Octopods are great at camouflage — they even surpass the ability of chameleons. But how does their camouflage system work?

The secret is chromatophores – skin cells that contain different pigments that are wired to the nervous system and to a radial muscle structure that allows it to change in length and thus change the color saturation of the cell. Each chromatophore is linked to the nervous system by a neuron, making the color change happen in less than a second.

 

They are also able to mimic textures via projections on the skin named papillae and can mirror the environment through iridophores —- reflective cells found in the octopi’s skin tissue.

Scientists have long been trying to develop the perfect camouflage system. Even though they succeeded to make objects invisible to the naked human eye, infrared cameras, that allow us to see temperature variations in colors would still be able to detect them because the electrical components that made visual camouflage possible would heat up, demonstrating their bluff.

So, researchers tried to imitate Mother Nature’s design: the octopod’s chromatophores. By combining special electrodes, wrinkled membranes, and an infrared-reflective coating, Chengyi Xu and colleagues created a synthetic device that mimics cephalopod skin. When applying an electrical current, the membrane expands, reflecting more light of a given wavelength. When the electrical current stops flowing through it, the membrane contracts. You can see below how the membrane reacts to electrical stimuli.

Researchers created a squid-shaped version of the device and analyzed its ability to camouflage. Then, they used an infrared camera to measure the changes in the device’s temperature. Scientists report that altering the reflectance of the device so that its temperature changed by a mere 2°Celsius was sufficient to mask its existence from an infrared camera.

Who knows — maybe in the future we could buy octopus skin clothes and activate them when encountering our exes.

Sinosauropteryx probably lived in open environments, similar to today's gazelles. Credit: Robert Nicholls.

Feathered dinosaur sported bandit mask and striped raccoon-like tail 130 million years ago

Sinosauropteryx probably lived in open environments, similar to today's gazelles. Credit: Robert Nicholls.

Sinosauropteryx probably lived in open environments, similar to today’s gazelles. Credit: Robert Nicholls.

Sinosauropteryx is the earliest dinosaur taxon we’ve found outside of Avialae (i.e. living dinosaurs, birds) that bears evidence of feathers. It lived during the early Cretaceous in the temperate climate of northeastern China some 130 million years ago. Now, scientists claim the dinosaur wore its plumage with style. Its eyes were patched with distinct coloring, like a masked bandit, while the tail was striped like a raccoon’s.

A mask carved in ‘stone’

The dwarf dinosaur didn’t grow larger than a meter from snout to tail. It was a theropod dinosaur (literally “beast-footed”), a large and diverse family which included the largest terrestrial carnivores ever to have made the earth tremble, among them the famed T. Rex.

When Sinosauropteryx was first described in 1996, it excited paleontologists all over the world due to its feathery coat. Suddenly, most dinosaurs weren’t necessarily scaly but, as subsequent discoveries showed, also feathered. The dinosaur’s plumage was rather fuzzy and primitive, though — ill-equipped for winged flight.

Pigment-storing eumelanosomes (left) and phaeomelanosomes (right) in the fossil feathers. Credit: University of Bristol.

Pigment-storing eumelanosomes (left) and phaeomelanosomes (right) in the fossil feathers. Credit: University of Bristol.

In 2010, researchers at the University of Bristol and the Zhonghe Zhou of the Institute of Vertebrate Paleontology discovered ancient color-producing sacs in fossilized feathers from the Jehol site in northeastern China. The pigment-packed organelles, called melanosomes, enabled the researchers to infer that the dinosaur likely had light and dark feathered stripes along the length of its tail. The darker regions of the tail were packed with phaeomelanosomes —  spherical organelles that produce and store the pigment responsible for the rusty reds of red-tailed hawks and red human hair — indicating they were russet-orange in color.

“We always tell introductory palaeontology students that things like sound and colour are never going to be detected in the fossil record,” paleontologist Michael Benton of the University of Bristol told Nature at the time. “Obviously that message needs to be reconsidered.

Quite the rascal. Credit: Fiann Smithwick.

Quite the rascal. Credit: Fiann Smithwick.

Now, in a new study published in the journal Current Biologyresearchers at the University of Bristol have produced an even more accurate picture of Sinosauropteryx.  Three fossils whose melanin pigment was still well preserved allowed the scientists to reconstruct the dark-hued plumage of the animals’ bodies. They found that a dark ‘mask’ was wrapped over the eyes of the dinosaur, which connected over the top the skull with other dark feathers that lined the back. At the base of the tail, the dark bands were thinner and more closely packed together. Closer to the tip, the bands were wider and spaced farther apart.

The plumage distribution is mapped out across each specimen, with feathers shown in brown, internal soft tissues and pigment from the eyes shaded gray, and vertebrate stomach contents in light blue. Credit: Current Biology.

The plumage distribution is mapped out across each specimen, with feathers shown in brown, internal soft tissues and pigment from the eyes shaded gray, and vertebrate stomach contents in light blue. Credit: Current Biology.

Sinosauropteryx‘s belly was probably white — a prime example of countershading, or Thayer’s Law, a method of camouflage in which an animal’s coloration is darker on the upper side and lighter on the underside of the body. The contrast counteracts the otherwise typical patterns of shadows and brightness cast by sunlight. Such camouflage would have been useful in evading predators and eluding prey.

“A clear darker dorsum and absence of pigmented plumage ventrally, with the light ventral side extending to the tail until at least the tenth caudal vertebra, conforms to what would be expected for countershaded camouflage adapted to reduce detection from visual predators and from potential prey,” the authors wrote in the paper.

Here’s where the really amazing part of this study comes in. Because countershading is inherently tied to the environment, the researchers were able to reconstruct Sinosauropteryx‘s environment as it likely looked like 130 million years ago.

The Differing Pattern of Predicted Self-Shadowing in Sinosauropteryx. Credit: Current Biology.

The Differing Pattern of Predicted Self-Shadowing in Sinosauropteryx. Credit: Current Biology.

The scientists first devised a 3-D model of the dinosaur, complete with its various colored patterns, then took pictures under different lighting conditions. This is how they found the dinosaur was adapted to open, sunny environments. Today, the part of China where the fossils were unearthed is a forest landscape.

An example of the inflated membrane programmed to form stone shapes. Credit: J.H. Pikul et al., Science (2017).

Artificial camouflage skin mimics the octopus’ unparalleled morphing

Octopi and cuttlefish are masters of disguise. Within a fraction of a second, they can morph their tissue and seamlessly blend with their surroundings, becoming indistinguishable from a rock or coral, for example. Taking cues from nature, researchers at Cornell University have devised their own ‘camouflage skin’ which stretches and morphs in 3D. The skin can be programmed to take all sorts of shapes.

An example of the inflated membrane programmed to form stone shapes. Credit: J.H. Pikul et al., Science (2017).

An example of the inflated membrane programmed to form stone shapes. Credit: J.H. Pikul et al., Science (2017).

The secret to cephalopods’ unrivaled camouflage lies within 3D bumps on the surface of their skin called papillae. In one-fifth of a second, the papillae can rise or retract, swiftly and reversibly morphing the animal’s surface into various textures like those belonging to seaweed or coral. The primary reason why the soft-bodied mollusks evolved this ability is for defense. Their flexible body has no bones so they can escape into small cracks, rocks, crevices, and even into bottles and cans from the seafloor. They can also use jet propulsion to quickly move through the water and escape predators. At the end of the day, however, these animals invested the most resources into camouflage because it pays off better to stay inconspicuous rather than constantly evade predators.

octopus camouflage

Simply amazing! Credit: Giphy.

In the closeup video below you can get a glimpse of how the papillae are actuated.

Cornell engineers worked closely with cephalopod biologists to design a controllable soft octopus-inspired actuator, reporting in the journal Science. First, cephalopod biologist Roger Hanlon and colleagues thoroughly described the papillae, which are muscular hydrostats — biological structures that perform an action and consist only of muscle with no bony frame. The human tongue is another prime example of a muscular hydrostat.

“Lots of animals have papillae, but they can’t extend and retract them instantaneously as octopus and cuttlefish do,” says Hanlon, who is the leading expert on cephalopod dynamic camouflage. “These are soft-bodied molluscs without a shell; their primary defense is their morphing skin.”

“The degrees of freedom in the papillae system are really beautiful,” Hanlon said in a press release. “In the European cuttlefish, there are at least nine sets of papillae that are independently controlled by the brain. And each papilla goes from a flat, 2D surface through a continuum of shapes until it reaches its final shape, which can be conical or like trilobes or one of a dozen possible shapes. It depends on how the muscles in the hydrostat are arranged.”

After nailing down the structure, function, and biomechanics of the cephalopod papillae, Cornell engineers developed synthetic tissue groupings that can be programmed to extend and retract. In order to closely mimic cephalopods as much as possible, the artificial papillae were constructed from a fiber mesh embedded inside a silicone elastomer. An algorithm determines how the pattern is set in the mesh using a laser so the final 3D shape of the ‘skin’ reaches the desired configuration. The silicone is simply inflated to turn the skin into a 3D object like a rock or the Graptoveria amethorum plant, as researchers demonstrated.

“Theoretically, you could do this really, really quick — milliseconds,” says study coauthor James Pikul.

This is not the first attempt at artificial dynamic camouflage. In 2014, Chinese researchers developed a thin, flexible 4-layer material that autonomously that changes appearance to match surroundings.

The method allows soft, stretchable materials to morph from 2D to a desired 3D shape, with a wide range of applications. For instance, the material can be tuned to reflect light in its 2D form and absorb light when it morphs into a 3D shape, which can be very useful when you want to manipulate temperature. Dynamic camouflage is also appealing to the Army Research Office which funded this research.

Nightjar bird.

A more limited range of color vision might help predators see through camouflage, research finds

Most animals can perceive fewer colors than humans can — while others can see many more. Scientists at the University of Exter have looked at the comparative advantages of di- and trichromatism in finding camouflaged birds in pictures to understand why so many species rely on this limited range of color vision.

Basic colors.

Sometimes less is more — but that doesn’t really stand for color receptor cells. Humans have three kinds of these cells on our retinas, so our vision revolves around three basic colors, making us trichromats. But a large number of other animals, including the majority of mammals today, are dichromats who only have two kinds of color receptor and see everything as a mix of only two colors. On the other hand, many bird species (and this one lady) are tetrachromats, and some invertebrates can pick up on many more colors.

But back to dichromats. Most of them are red-green color blind, and that’s also the most common type of color blindness in humans. Moreover, some primate species show color vision polymorphism, meaning certain females are trichromats but most individuals are dichromats. Add all this evidence together, and it begs the question — is there an evolutionary advantage for seeing only two colors instead of three? To find out, a team from the University of Exter has created an online computer game and unleashed it upon the web, where more than 30,000 people played it.

The concept was pretty simple: players were shown photographs either in normal color or in simulated dichromatic vision. There were camouflaged nightjar birds or their nests, containing eggs, somewhere in the image — and the players had to find them.

Nightjar bird.

Example of a nightjar seen in trichromat (left) and dichromat (right) vision.
Image credits University of Exeter.

Seeing a more limited range of colors should make dichromat predators more adept at finding prey since there’s less color, so to speak, to help hide a well-camouflaged dinner. Dichromats should thus have an easier time differentiating between light and dark areas and finding hidden objects, for example — an advantage any aspiring predator would want.

But the team was surprised to find that participants looking at trichromat photos were actually faster at finding the nightjars and eggs that their counterparts. There were large variations in the performance of dichromat players from photo to photo — depending on factors such as camouflage patterns or brightness. Furthermore, over the course of the game, dichromats improved their game faster than trichromats, and by the end of the game, both groups performed equally well.

So it is possible that their performance was worsened as their brains learned the ins and outs of dichromatic vision. It may be that, given a longer period of time to adjust, they could become even better than trichromats at spotting the eggs.

” These results suggest there are substantial differences in the cues available under viewing conditions that simulate different receptor types, and that these interact with the scene in complex ways to affect camouflage breaking,” the team concludes.

 

The paper “Relative advantages of dichromatic and trichromatic colour vision in camouflage breaking,” has been published in the journal Behavioural Ecology.

Insects were masters of camouflage even 100 million years ago

Lacewing larva with a back basket: Credit: Bo Wang, Nanjing

Lacewing larva with a back basket: Credit: Bo Wang, Nanjing

Insects are among the best disguise artists in the world. A few are so well-disguised they’re incognito almost anywhere, like the stick insects who use their twig-like bodies to become virtually invisible just by holding still. The findings of a group of Chinese researchers led by Bo Wang suggests this striking behaviour evolved at least 100 million years ago, as revealed by dozens of insects trapped in fossilized amber with their camouflage still intact.

Wang and colleagues at Chinese Academy of Sciences in Nanjing painstakingly went through 300,000 amber fossils from around the world, 39 of which were presented in a new paper published in the journal Science AdvancesThe authors write that these insects employed complex camouflage techniques, not at all different from the kind we see today. This includes cloaking themselves with plants, grains of sand, soil, leaves and even the carcasses of their prey.

The discovery of such an extensive use of camouflage among so many species came as a surprise to the researchers involved, given Cretaceous ecosystems and plants are systematically different than present day ones.

“These are very rare fossils, which give us unique insights into life more than 100 million years ago”, says Dr. Torsten Wappler of the Steinmann-Institute of the University of Bonn, who joined Dr. Wang and Professor Rust to classify these oldest examples of camouflage.

One of the most interesting behaviours was that of some larvae who used grains of sand as a sort of armour to protect themselves against spider bites. To cover themselves in sand better, the larvae adapted special legs which can turn 180 degrees, allowing them to transport the sand using their backs.

Myrmeleontoid larvae, flecked with debris. Credit: Wang et al

Myrmeleontoid larvae, flecked with debris. Credit: Wang et al

Other insects employ more classical forms of camouflage like using plant residue to blend with the surroundings and become impervious to predators. Though it may sound simple, playing hide and seek is, in fact, a very complex behavior. It requires, first of all, recognizing which materials from nature are suitable, then carry or process these materials.

Perhaps the most striking of all the amber fossils, all of whom were larvae by the way, were the lacewings. These insects attacked Cretacious scorpions then used their mouthparts to effectively suck them dry until nothing but an exoskeleton remained. The lacewing then puts its scorpion shell on its back, it old outlines now no longer visible. This camouflage protects the larvae against predators but also makes attacking new prey easier.

“With this ‘disguise’, the lacewing larva pretends to be someone completely different”, says Prof. Dr. Jes Rust of the Steinmann-Institute of the University of Bonn. “Using the pieces of its prey, it even takes on the smell of the pseudoscorpion”.

The researchers say the insects must have evolved all of these camouflage abilities independently since the analyzed species weren’t related. It would be interesting, however, to find out if today’s insects who use camouflage also independently evolved this ability or what we see today was inherited from species at least 100 million years old.

“Apparently, camouflage offers many advantages for the user, for which reason it was ‘invented’ multiple times during evolution,” Rust added.

Image: Rock'n'Critters

The filefish smells like its camouflage to avert predators

The world isn’t just fight or flight, there’s also a third option: hide. The reef-dwelling fish (Oxymonacanthus longirostris), also known as the harlequin filefish,  is a true master of disguise that not only blends with its environment to avert itself from the gaze of a hungry predator, it also dissimulates its odor. In other words, the fish not only looks like coral, it smells like coral too.

Smells like coral

Image: Rock'n'Critters

Image: Rock’n’Critters

 

The discovery was made made by an international team of biologists and reported today in the Proceedings of the Royal Society BTo test whether or not the filefish actually uses a chemical camouflage, several specimens were placed inside a tank with a cod – one of it’s natural predator. To neutralize the effect of the visual camouflage, the filefish were hidden inside perforated containers within the aquarium so that the cod could only smell, and not see, its prey. When the filefish’s last meal was the same with the species of coral that made its environment, the cod was much less likely to hang around the container. Clearly, the filefish is capable of somehow transmitting the ingested chemicals to its outer skin then diffusing them into the water to match the coral odor. It’s odor disguise is so good that it even fooled crabs who were given a choice between a meal consisting of their favorite corals and a filefish that fed on their favorite corals. More often than not, the crabs chose the filefish.

It’s quite a disguise, but not unique. Caterpillars, for instance, also incorporate chemicals from their food and incorporate these into their skin, releasing them as volatile compounds to fool predators. This is, however, the first instance this behavior has been identified in a vertebrate.

via SciMag

Lichen Spider

10 Fantastic Animals That Use Bark Camouflage

When you’re high up in the food chain, nature can be truly awesome. You can stroll around, contemplate its hidden beauties, all without fear of getting eaten. Not all beings are as lucky as us humans, though. To survive, many animals have learned to adapt defense mechanisms, but most often than not the best way to avoid getting killed is not to fight, nor fly, but hide. This is where camouflage comes in.

There are many types of camouflage animals employ. There’s concealing coloration (white rabbits in the snow), mimicry (when they try to look like other more dangerous animals), disruptive coloration (spots, stripes, others patterns – see zebras, leopards) and disguise (blending with the surrounding to look like an object). Below you’ll be amazed to find 10 animals that employ this latter form of camouflage, all of which use tree barks as their target object. Were you able to see

Mossy Leaf-Tailed Gecko

Mossy Leaf-Tailed Gecko

Grey Tree Frog

Grey Tree Frog

Grey Cicada

Grey Cicada

Casque head Chameleon

Casque head Chameleon

Lichen Spider

Lichen Spider

Underwing Moth

Underwing Moth

Peppered Moth

Peppered Moth

Owl Fly Larva

Owl Fly Larva

Eastern Screech Owl

Eastern Screech Owl

A macro shot of a Blue Poison Dart Frog (Dendrobates Azureus). You wouldn't want to eat this fellow, and its bright colours serve as a warning. (c) MSU

Camouflage or bright colours: what’s better for survival?

The wild is often home to a game of hide or seek, and animals need to be well adapted to their part of the game. For those who are constantly juggling the role of prey, however, the game seems to always favor them less. We, as humans, have little direct contact with these underlying mechanics of survival, as we sit comfortably on the crown spot of the food chain. For the millions of species out there fighting for survival this is an entirely different matter, but of course nature has granted each of them with a trait or skill.

A macro shot of a Blue Poison Dart Frog (Dendrobates Azureus). You wouldn't want to eat this fellow, and its bright colours serve as a warning. (c) MSU

A macro shot of a Blue Poison Dart Frog (Dendrobates Azureus). You wouldn’t want to eat this fellow, and its bright colours serve as a warning. (c) MSU

It all boils down to avoid being eaten, and some of the paths evolution has taken involve hiding or poison. Being a poisonous species has its benefits and downfalls; for one the chances of you being eaten plummet as the trait is accompanied by bright colouring (yellow, black, red) which predators have learned to avoid, but secreting poison comes at huge energy expenses, so not a lot of species can afford it. The most beaten path involves hiding through camouflage. Some species however choose to go in between: they flatter they bright, venomous-like colouring out in the open, despite they lack the accompanying poison altogether. Their game is all bluff.

How dangerous is this approach? A team of researchers Michigan State University analyzed how coluor-coded communications evolve and found that this takes place in gradual steps, instead of a sudden leap for garish colouring adoption. This tells us that the route pass the middle ground from simple camouflage to poison mimicker is layered with many perils, which few may undergo.

“In some cases, nonpoisonous prey gave up their protection of camouflage and acquired bright colors,” said Kenna Lehmann, who conducted the research. “How did these imitators get past that tricky middle ground, where they can be easily seen, but they don’t quite resemble colorful toxic prey? And why take the risk?”

 MSU scientists show that nontoxic imposters, like king snakes, benefit from giving off a poisonous persona, even when the signals are not even close.

MSU scientists show that nontoxic imposters, like king snakes, benefit from giving off a poisonous persona, even when the signals are not even close.

Colourful impostors

The higher the risk, the higher the reward it seems. Predators, evolutionary conditioned to stay away from poisonous species, react to the impersonations and avoid eating the imposters. It seems to work. For instance coral snakes are truly toxic animals, while king snakes are not, but the two very much look alike. So, why don’t the imitators develop poison of their own and be done with it? The transition is in itself extremely costly – and developing poison comes at tremendous energy expenditure.

“Leaving the safety of the cryptic, camouflage peak to go through the exposed adaptive valley over many generations is a dangerous journey,” Lehmann explained. “To take the risk of traversing the dangerous middle ground – where they don’t look enough like toxic prey – is too great in many cases. Toxins can be costly to produce. If prey gain protection by colors alone, then it doesn’t make evolutionary sense to expend additional energy developing the poison.”

For the study, the scientists used evolving populations of digital organisms in a virtual world called Avida. Using this model, the researchers looked at how specialized programs compete and reproduce. The software is developed in such a manner that mutations occur when Avida beings reproduce, and thus scientists digital organisms evolve, just like living things.

Findings were reported in the journal PLOS ONE.

(C) Youtube screenshot

Squids-protein modified bacteria used to develop camouflage coating

(C) Youtube screenshot

(C) Youtube screenshot

Loliginidae, also known as pencil squids, are formidable animals that can change their colour matching their surroundings really fast and effortlessly. For centuries the only thing man has learned from them is how tasty they are. Now, researchers at University of California, Irvine, found there’s much more to them then a simple calamari dish. The scientists used the protein that offers the squids’ ability to hide from both enemy and pray to adapt their own bio-coating  that mimic’s the squid’s skin.

The squid can change its color within a fraction of a second through a a structural protein called reflectin, which basically works by dynamically changing the squid’s skin light reflection. The team of researchers at UCI developed a method to produce reflectin, which they then introduced in a common bacteria population. The modified bacterial population were then used to make thin, optically active films that mimic the skin of a squid.

The real kicker and innovation of this work is that the resulting camouflage material not only keeps things hidden from sight, but also from infra-red readings – the de facto standard in military identification.

“The novelty of this coating lies in its functionality within the near-infrared region of the electromagnetic spectrum, roughly 700 to 1,200 nanometers, which matches the standard imaging range of most infrared visualization equipment,” said research leader Alon Gorodetsky . “This region is not usually accessible to biologically derived reflective materials.”

With the appropriate chemical stimuli, the films’ coloration and reflectance can shift back and forth, giving them a dynamic configurability that allows the films to disappear and reappear when visualized with an infrared camera. Using such a biofilm, one could potentially coat just about any surface,  potentially allowing many simple objects to acquire camouflage capabilities.

“We’re trying to develop something that you could essentially use as reconfigurable infrared reflective paint so that you’d be able to disguise yourself,” research leader Alon Gorodetsky said, according to a report from Chemistry World. “There’s really not much out there in terms of inexpensive, biodegradable non-toxic materials that can be changed on the fly.”

What about shape-shifting suits? That’s a real possibility, according to the researchers. If you ever read P.K. Dick’s A Scanner Darkly, you might be stunned by the prospect.

“Our long-term goal is to create fabrics that can dynamically alter their texture and color to adapt to their environments,” Gorodetsky said. “Basically, we’re seeking to make shape-shifting clothing – the stuff of science fiction – a reality.”


It’s worth noting that a Harvard team devised a robot that mimics squid camouflage capabilities back in 2012. Read about it here.

Findings appeared in the journal Advanced Materials.