Tied to the immense predation pressure under which these animals live is their ability for camouflage. Perhaps their most astonishing specialization, it provides an inexhaustible “magic well” for those who study them. The octopus changes color so rapidly that it out-chameleons the chameleon. Roger Hanlon, a scientist at the Marine Biological Laboratory in Woods Hole, Massachusetts, has collected rare underwater footage of octopuses in action. All we see at first is a clump of algae on a rock, but hidden among it is a large octopus indistinguishable from its surroundings. When the approaching human diver scares the animal, it turns almost white, revealing that it represented almost half the clump of algae. It speeds away while shooting a dark cloud of ink, which is its secondary defense. The animal then lands on the sea floor and makes itself look huge by spreading all its arms and stretching the skin between them into a tent. This frightening expansion is its tertiary defense.
When this video clip is slowed down and played backward, it is easy to see how superb the original camouflage was. Both structurally and color-wise, the large octopus had made itself look exactly like an algae-covered rock. It did so by making its chromatophores (millions of neurally controlled pigment sacs in its skin) match their surroundings. But instead of exactly mimicking its background, which is impossible, it did so just well enough to fool our visual system. And it probably did more than that, since the octopus also takes other visual systems into account. Humans see no polarized or ultraviolet light and don’t have great night vision, whereas the octopus’s camouflage needs to trick all these visual capacities. In doing so, it draws on a limited set of patterns that it has in stand-by mode. Turning on one of these “blueprint” patterns allows it to blend in in a fraction of a second. The result is an optical illusion, but one realistic enough to save its life hundreds of times.28
Sometimes an octopus mimics an inanimate object, such as a rock or plant, while moving so slowly that one would swear it is not moving at all. It does so when it needs to cross an open space, an activity that exposes it to detection. Imitating a plant, the octopus waves some of its arms above itself, making them look like branches, while tiptoeing on three or four of its remaining arms. It takes tiny little steps in line with the water movements. If the ocean is wild, plants sway back and forth, which helps the octopus disguise its steps by swaying in the same rhythm. On a waveless day, on the other hand, nothing else moves, so the octopus needs to be extremely careful. It may take twenty minutes to cross a stretch of sea floor that it otherwise might have crossed in twenty seconds. The animal acts as if rooted to the spot, counting on the fact that no predator will take the time to notice that it is actually inching forward.29
The champion of camouflage, finally, is the mimic octopus, a species found off the coast of Indonesia that impersonates other species. It acts like a flounder by adopting this fish’s body shape and color as well as its typical undulating swimming pattern close to the sea floor. The repertoire of this octopus includes adopting the likeness of a dozen local marine organisms, such as lionfish, sea snakes, and jellyfish.
We don’t know exactly how octopuses achieve this astonishing range of mimicry. Some of it may be automated, but there is probably also learning involved based on observations of other creatures and adoption of their habits. As primates, we find it impossible to relate to these remarkable capacities, and we may hesitate to call them cognitive. We tend to view invertebrates as instinct machines, arriving at solutions through inborn behavior. But this position has become untenable. There are too many remarkable observations—including the deceptive tactics of cuttlefish, close relatives of the octopus.
Male cuttlefish courting a female may trick rival males into thinking there is nothing to worry about. The courting male adopts the coloring of a female on the side of his body that faces his rival, so that the latter believes he is looking at a female. But the same male keeps his original coloring on the female’s side of his body in order to keep her interested. He thus courts her surreptitiously. This two-faced tactic, called dual-gender signaling, suggests tactical skills of an order that we might expect in primates but not mollusks.30 Hanlon rightly claims that cephalopod truth is stranger than fiction.
Invertebrates will probably continue to challenge students of evolutionary cognition. Being anatomically quite different yet facing many of the same survival problems as the vertebrates, they offer fertile grounds for convergent cognitive evolution. Among the arthropods, for example, we find jumping spiders known to trick other spiders into thinking that their web contains a struggling insect. When the web-owner hurries over for the kill, she herself becomes the prey. Instead of knowing at birth how to enact a trapped insect, jumping spiders seem to learn how to do so by trial and error. They try out a kaleidoscope of random pluckings and vibrations on the silk of another spider, using their palps and legs, while taking note which signals best lure the owner toward them. The most effective signals will be repeated on future occasions. This tactic allows them to fine-tune their mimicry to any victim species, which is why arachnologists have begun to speak of spider cognition.31
And why not?
When in Rome
To our surprise, chimps turn out to be conformists. Copying others for one’s own benefit is one thing, but wanting to act like everybody else is quite another. It is the foundation of human culture. We discovered this tendency when Vicky Horner presented two separate groups of chimpanzees with an apparatus from which food could be extracted in two different ways. The apes could either poke a stick into a hole to release a grape or use the same stick to lift up a little trap and a grape would roll out. They learned the technique from a model: a pretrained group member. One group saw a lifting model, the other a poking model. Even though we used the same apparatus for both groups, moving it back and forth between them, the first learned to lift, and the second to poke. Vicky had created two distinct cultures, dubbed the “lifters” and the “pokers.”32
There were exceptions, though. A few individuals discovered both techniques or used a different one than their model had demonstrated. When we retested the chimps two months later, though, most of the exceptions had vanished. It was as if all the apes had settled on a group norm, following the rule “Do what everyone else is doing regardless of what you found out by yourself.” Since we never noticed any peer pressure nor any advantage of one technique over the other, we attributed this uniformity to a conformist bias. Such a bias obviously fits my ideas about imitation guided by a sense of belonging as well as what we know about human behavior. Members of our own species are the ultimate conformists, going so far as abandoning their personal beliefs if they collide with the majority view. Our openness to suggestion goes well beyond what we found in the chimps, yet it seems related. This is why the conformist label stuck.33