One afternoon in late August, Tessa Montague, a postdoc in neuroscience at Columbia University, stood in a windowless lab at the Zuckerman Institute several floors below street level peering at a dwarf cuttlefish, an octopus relative about the size of a human palm. The cuttlefish swam in a saltwater tank scattered with fake algae and rocks, its skirtlike fins fluttering, as dark and light bands rippled along its body like shifting shadows. For a moment, the undulating bands stopped moving across its skin. “We don’t know what they mean or why they do it,” Dr. Montague said, as the bands began rippling again. “But they’re kind of amazing.” Around her, more than 100 similar tanks, housing over 200 dwarf cuttlefish, filled the room with the hum of water pumps and the smell of brine.
In one tank, a cuttlefish had darkened to conceal itself amid a clump of fake algae. In another, the resident had white spots running down its body. A third cuttlefish had turned its skin pale as it hovered near the top of its tank, as if waiting for a meal.
Coleoid cephalopods, the group that encompasses cuttlefish, octopus and squid, have mystified scientists for centuries. Endowed with large brains that evolved entirely independently of vertebrates’, they can solve problems, form memories and engage in social behavior. Aristotle, who observed cuttlefish in a bay on the Greek island of Lesbos, called them “the most cunning” of soft-bodied animals.
Some cephalopods, including cuttlefish, can camouflage themselves with stunning precision, changing the pattern, color and texture of their skin to match coral reefs and sandy seabeds. Scientists have long wanted to understand the neural basis for that otherworldly transformation. How does the cuttlefish — which studies suggest is colorblind — take in the visual world and project it on its skin in as little as a second? “It’s showing you its perception of the world,” Dr. Montague said. “No other animal can show you what it sees or tell you what it sees except a human.” Dr. Montague and her colleagues have taken a significant step toward being able to understand the phenomenon.
In September they announced that they had created the first transgenic cuttlefish by successfully inserting foreign genes into its DNA, which were passed on to subsequent generations. Their goal is to engineer a cuttlefish whose neurons flash each time they’re active, allowing researchers to map how camouflage is generated in the brain. “If we can look inside the brain during camouflage,” Dr. Montague said, “we can see how the brain is representing the visual world.” ‘Like grabbing a cloud’ Cuttlefish change color by manipulating millions of pigment cells, called chromatophores, which act like color pixels in a television display. Each chromatophore holds a single pigment, and the cells are arranged in layers: yellow or orange on top, red in the middle, and brown or black at the bottom.
Tiny muscles, controlled by motor neurons, cause the chromatophore to expand or shrink, displaying more or less pigment. The layering of pigment cells produces additional hues, and the animal has other specialized cells that can create iridescence, or shimmer. Some species can produce a wider range of colors and patterns than others, helping them to evade predators, hunt and communicate.
The flamboyant cuttlefish, a species native to the waters of the Indo-Pacific, can produce a kaleidoscope of vibrant red, yellow and purple on its skin. The cuttlefish’s ability to match its environment occurs so quickly that it seems like a reflex, said Cliff Ragsdale, a neurobiologist at the University of Chicago. Yet it’s so complex and variable that it suggests a higher level of cognitive processing — “like, for us, the production of languages,” he said. “There are so many puzzles to it.” To camouflage, a cuttlefish must first take in the scene, select an appropriate pattern and then enlist hundreds of thousands of chromatophores to produce it.
Past studies suggest that ...
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