Color-Blind Cephalopods Perform Colorful Camouflage Tricks
Roger Hanlon has studied octopi, squid and cuttlefish for decades. He stands in awe of their ability to camouflage themselves. In a Primer article for Current Biology,1 he detailed some of their sleight-of-skin magic tricks.
His article has frames from a movie clip that show an octopus changing its skin from plain to mottled in milliseconds, then to almost pure white in two seconds. It’s not just the color that changes. Cephalopods also have the ability to change the texture of their skin from smooth to dimpled. They can also change the pattern from plain to mottled to what Hanlon calls “disruptive” – bold patterns that would include stripes and “light and dark patches of varying shapes, scales and orientations, and some patches [that] are usually of high contrast.”
For such mechanisms to work, the octopus or cuttlefish has to have (1) eyes that can sense what kind of background they’re against, (2) brains that can process the information and send the appropriate signals to the skin, and (3) skin cells tied to neurons that can respond quickly and draw from a large suite of possible patterns. These cells include chromatophores (color cells), iridophores (reflecting cells) and papillae (skin cells that produce bumps). Putting it all together,
Rapidity of visual change is accomplished by direct neural control of chromatophore organs, which are cytoelastic sacs of pigment with radial muscles attached around the periphery. Each muscle is innervated by motoneurons that originate in the lower motor centers of the brain, and they travel without any synapse to each chromatophore organ. Third, camouflage benefits from both optical and physical three-dimensional effects, the latter being due chiefly to the changeable skin papillae. Note in Figure 2 how the three-dimensionality of the skin is also under fine motor control. Curiously, although papillae expression is regulated by visual input, neither this nor the biomechanics of how the papillae operate as a muscular hydrostat in the skin has been studied in any detail.
So here is a field of study ripe for investigation by biophysicists, neurologists, optical specialists, and specialists in a variety of fields. New techniques with underwater computers and spectrometers have just begun, he said. Hanlon’s team has performed experiments for five years with cuttlefish. They put them against all kinds of background patterns and watched how their camouflage systems responded. Surprisingly, it appears they are color blind! Yet “Their color matches to natural visual backgrounds appear to be excellent,” he said. How do they do it? Stay tuned: “we continue to search for mechanisms that help them achieve color-blind camouflage.”
One of the most intriguing effects the octopus can achieve is the ability to send hidden messages. Hanlon explains:
Other features of the cephalopod dynamic camouflage system have yet to be studied in detail. The skin, for example, is a marvelous example of rapid, highly coordinated optical malleability: pigmentary and structural coloration are combined in many ways to achieve vastly different appearances, both from close-up and distant viewing. The directional structural reflectors known as iridophores (which in most animals are passive reflectors) are not only under active control by cephalopods, but they produce polarized signals that pass unaffected through the overlying pigmented chromatophores. This raises the possibility that a dynamically camouflaged cephalopod could be simultaneously sending a ‘hidden’ signal to a conspecific, because cephalopods can perceive polarized light while most of their predators cannot, while remaining well camouflaged using pigmented chromatophores.
(cf. 12/15/2006). If true, this indicates that cephalopods already mastered another human trick: hiding in plain sight. Cryptologists have considered it a challenging puzzle to communicate a secret message in the presence of an adversary, like two jailmates communicating a secret to one another while an active warden is watching them. Called steganography, the art of concealing a message in plain sight is a lively subject in computer technology. You can find software programs that will hide or detect secret messages embedded in pictures or sound files, for instance. Here, it appears that octopi, squid and cuttlefish have known this trick all along.
Lastly, an octopus can alter its whole shape to mimic something else. Camouflage works well when you are hovering still, but what about when you need to move about for foraging or finding a mate? Hanlon shows a picture of an octopus shaping its body like a flounder. It not only imitates the overall shape, but mimics the fins, the behavior and speed of the fish.
The “mimic octopus” of Indonesia has even more tricks up its sleeve. It can look like a lionfish or sea snake, among other things (see MarineBio.com and picture of it looking somewhat like a rabbit). Some of these tricks are illustrated in motion in the film series Incredible Creatures that Defy Evolution. One episode also shows the cuttlefish with rapid-fire lighting effects that can hypnotize its prey.2
1Roger Hanlon, “Primer: Cephalopod dynamic camouflage,” Current Biology, Volume 17, Issue 11, 5 June 2007, Pages R400-R404, doi:10.1016/j.cub.2007.03.034.
2For the record, Roger Hanlon is an evolutionist with no connection to these films.
Sadly, we now have to switch from the Amazing Facts thought pattern to the Dumb Ideas thought pattern. Roger’s excellent article was marred by repeated references to evolution having accomplished these things. Nowhere did he explain how a blind process could achieve them, just that they did. Notice how he puts have evolved in past tense as a matter of assumed fact, right alongside incredible wonders of design:
- Cephalopods have evolved a different life history tactic: with their keen vision and sophisticated skin – with direct neural control for rapid change and fine-tuned optical diversity – they move where they wish and can adapt their body pattern for appropriate camouflage against a staggering array of visual backgrounds….
- How many camouflage patterns are there, and how many visual tricks have evolved to deceive visual predators?
- While evolution has produced body colorations and patterns of bewildering diversity, we may be observing a trend in which certain effective pattern types are conserved across phyla and ecological habitat.
- We do not yet understand the type of mimicry involved (for example, Batesian or Mullerian), the evolution of this form of camouflage, or the visual stimulation that may evoke it.
- Future studies on fish vision would help us understand not only the anatomical organization of cephalopod pigments and structural reflectors, but the details of the whole-animal patterns that have evolved in response to the wide array of predator visual systems.
The worst example is right at the end of the article. Evolutionists are the worst offenders at question-begging among educated people. Read the following paragraph and ask yourself how any intelligent person could say such a thing, linking art, science, high technology and system-wide complexity to Darwin’s theory of blind chance – unless he had been brainwashed aforethought that miracles are possible in Charlie’s web of belief:
The subtle ways in which edges, shadows, outlines, patterns, colors, contrast and papillae are used by animals for camouflage or communication also seem to have much in common with art, photography, landscape architecture and related fields, because light and dimensionality are being manipulated in similar fashion. When watching the video from Figure 1, the aphorism “truth is stranger than fiction” comes to mind, especially when compared to the ‘invisibility cloaks’ that have recently received so much attention in the popular media. The speed and fluidity with which cephalopods simultaneously maintain predator awareness, search for prey, and coordinate a camouflage body pattern with each microhabitat offers insight into how a complex biological organism works as an intact system. There are great challenges yet to confront in understanding the sensory and behavioral interactions between visual predators and prey, and it is humbling yet intriguing to think that such an ancient lineage as the mollusks has evolved such a sophisticated system with which to test camouflage.
Thus an otherwise stimulating paragraph was deflated by those two little words, “has evolved.” For extreme intellectual schizophrenia and the worst case of begging the question in recent memory, this paragraph easily wins Stupid Evolution Quote of the Week.