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.<\/p>\n
For a moment, the undulating bands stopped moving across its skin. \u201cWe don\u2019t know what they mean or why they do it,\u201d Dr. Montague said, as the bands began rippling again. \u201cBut they\u2019re kind of amazing.\u201d<\/p>\n
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.<\/p>\n
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\u2019, 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 \u201cthe most cunning\u201d of soft-bodied animals.<\/p>\n
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 \u2014 which studies suggest is colorblind \u2014 take in the visual world and project it on its skin in as little as a second?<\/p>\n
\u201cIt\u2019s showing you its perception of the world,\u201d Dr. Montague said. \u201cNo other animal can show you what it sees or tell you what it sees except a human.\u201d<\/p>\n
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<\/a> by successfully inserting foreign genes into its DNA, which were passed on to subsequent generations.<\/p>\n Their goal is to engineer a cuttlefish whose neurons flash each time they\u2019re active, allowing researchers to map how camouflage is generated in the brain. \u201cIf we can look inside the brain during camouflage,\u201d Dr. Montague said, \u201cwe can see how the brain is representing the visual world.\u201d<\/p>\n \u2018Like grabbing a cloud\u2019<\/p>\n 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.<\/p>\n 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.<\/p>\n 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.<\/p>\n The cuttlefish\u2019s 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\u2019s so complex and variable that it suggests a higher level of cognitive processing \u2014 \u201clike, for us, the production of languages,\u201d he said. \u201cThere are so many puzzles to it.\u201d<\/p>\n 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 the animal doesn\u2019t copy the scene pixel by pixel. Instead, it seems to mostly rely on texture.<\/p>\n Imagine looking at a patch of sand on the seabed, then closing your eyes. You probably would not be able to picture the precise location of every individual grain of sand. But you could probably still remember the way the seabed looked \u2014 the coarseness of the grains, say, or how packed they were. You could still envision and describe those properties without knowing where each grain of sand was. That is texture.<\/p>\n The cuttlefish brain may be compressing the texture of the visual world \u2014 such as sand or rocks \u2014 into a set of numbers, then decompressing those back into a recreation of that world on the skin, said Erica Shook, a Ph.D. candidate at Columbia working with Dr. Montague.<\/p>\n Scientists want to understand the whole loop: how the cuttlefish encodes the information and then outputs the pattern. Visual statistics may help them identify which features of the environment the cuttlefish is trying to match. Then, by studying the flashing neurons in its brain, they may be able to trace how the brain turns that information into a pattern on the animal\u2019s skin.<\/p>\n But the phenomenon also depends on perception, Ms. Shook said: Good camouflage is whatever manages to fool the observer. \u201cAnytime you\u2019re having to deal with perception, things get very, very hard,\u201d she added.<\/p>\n Roger Hanlon, a marine biologist at the Marine Biological Laboratory in Woods Hole, Mass., who has studied camouflage for more than five decades, said that measuring camouflage was \u201ckind of like grabbing a cloud.\u201d<\/p>\n \u201cYou see a cloud, you know what it is, you grab it, but you don\u2019t get anything in your hand,\u201d he said. \u201cCamouflage is like that. You know that it\u2019s doing something visually, but trying to put numbers to it is very difficult.\u201d<\/p>\n Caring for cephalopods<\/p>\n To better understand how the cuttlefish performs its magic, Dr. Montague first needed to choose the right species to study. Past studies had used the European cuttlefish \u2014 the same species Aristotle studied in the Aegean Sea over 2,000 years ago. Dr. Montague chose the dwarf cuttlefish instead, a smaller species native to the tropical waters of the central Indo-Pacific that develops faster and lives as long as a year.<\/p>\n Caring for and breeding cephalopods is notoriously difficult. They are sensitive to water quality and temperature. Some species are cannibalistic; others grow too large to be easily maintained in a lab. And almost all octopuses lay just one clutch of eggs in their lifetime.<\/p>\n At Columbia, the research team mixes its own saltwater for the tanks and orders grass shrimp overnight from Florida by FedEx Priority. \u201cThe animals demand perfection,\u201d said Connor Gibbons, the lab\u2019s cephalopod manager. (Mr. Gibbons wears a gold wedding ring that was cast in a mold made of cuttlebone, the cuttlefish\u2019s internal shell.)<\/p>\n Creating a transgenic cuttlefish required an understanding of the species\u2019 behavior, genetics and development, and Dr. Montague, with funding from the Howard Hughes Medical Institute, has spent the better part of a decade building her knowledge of all three. \u201cBut transgenesis is by far the most difficult,\u201d she said.<\/p>\n How to make a cuttlefish glow<\/p>\n For the Columbia team, a transgenic cuttlefish would serve as an animal model: an organism specially designed for laboratory studies, with neurons that light up to identify where and how camouflage works in the brain.<\/p>\n