How does a cuttlefish lie to its rivals while courting a mate?

When a male cuttlefish courts a female while rival males are nearby, he can send two messages at once: he displays one pattern of color and texture facing the female, an inviting courtship signal, while simultaneously showing an entirely different pattern, one that mimics a female, on the side of his body facing the other males. It's a live, split-screen lie, and it works because cuttlefish have specialized skin cells, chromatophores, that rapidly change the color, opacity and reflectiveness of their skin.

That kind of display is just one tool in a much larger animal communication toolkit: the transfer of information between animals that changes a receiver's behavior, sometimes sent deliberately, as in a courtship dance, and sometimes not, as when a predator's scent accidentally warns off prey. For a signal to stick around across generations, both sender and receiver generally need to benefit somehow, so the two sides are thought to evolve together over time. A parent herring gull's red-spotted bill works this way: the chick taps the spot, which triggers the parent to regurgitate food, a simple but precise visual signal both birds rely on.

Facial and bodily cues carry real information too. Blue-and-yellow macaws have been shown to blush during friendly interactions with a familiar caretaker, and mice, according to one study, show five distinct facial expressions that track rising pain, including tightened eyes and changed whisker position. A female olive baboon's body even runs on a built-in calendar: when she starts to ovulate, part of her skin swells and turns bright red or pink, a signal to males that she is ready to mate.

Sound carries its own kind of precision. Vervet monkeys give a distinct alarm call for each of their four predators, and other monkeys respond correctly to each: climbing a tree for the python call, ducking for cover at the eagle call. Prairie dogs go even further, apparently packing details like a predator's type, size and speed into their calls. And not every animal even needs a voice: crickets, grasshoppers, and many other arthropods rub body parts together to make sound, a technique called stridulation, while rattlesnakes buzz their tails, gorillas beat their chests, and some birds clack their bills, each producing a signal without a single vocal cord.