Rainbow squid

The rainbow squid is an enormous, rorqual whale-sized squid, from the Global Ocean, 200 million AD, in The Future is Wild.

Sometimes, several flocks of ocean flish will gather above one whirling silverswimmer shoal. Suddenly, a rainbow squid tentacle will snap from the water surface, seizing a flish and disappears. The shoal then vanishes as well, and in its place appears a broad, dark shape - the back of the enormous animal drifting just below the surface.

Part of the shoal is not a shoal at all, but the changing pattern on the skin of this beast. With a body 60-75 feet (20-25 meters) long, and tentacles of similar length, this is the biggest animal in the Global Ocean.

Like other cephalopods, the rainbow squid has the ability to change color at will. It can merge with the ubiquitous green of the ocean and hide from sight; or flash up a sudden dramatic display to scare away would be predators or to attract a mate. It can even produce a flowing pattern of colored patches to mimic the swirling motion of a shoal of silverswimmers - bait for the ocean flish on which it feeds.

The rainbow squid has shaken off the evolutionary manacles of its ancestors to achieve this feat. While the lifespan of a typical squid of previous times was only two years, other, simpler mollusks can live for decades. Once the squid had escaped this live-fast-die-young cycle, it was able to unlock its evolutionary potential. In the Global Ocean, the rainbow squid has virtually no predators (few other creatures would dare to take on such a giant) and can now live for up to a century. With this extended lifespan has come a highly-evolved intelligence and sophistication.

The sophistication of the rainbow squid is evident in the way it controls changes of color, through pigmented muscular sacs on the surface of its skin called chromatophores. These can be expanded or contracted at will, producing color changes or flowing patterns over the surface of the whole animal. Each chromatophore is controlled by its nerve, part of a complex nervous system connected to the brain.

The rainbow squid's large brain enables it to command the flashes, pulses and rippling patterns that make up the display across its back. Its senses are acute. Indeed, it is so sensitive to its surrounding environment that it is able to choose the appropriate display for any situation: attraction, warming or bait for prey. These color pigments are present in each chromatophore, and combinations of these can produce an almost infinite variety of patterns. Some even contain symbiotic, luminous bacteria, enabling the squid to produce displays of light.