Cuttlefish camouflage is much more complex and mind-boggling than initially thought

The ability of cuttlefish to instantly “vanish” by mimicking their surrounds is nothing short of astounding. New research suggests that the process through which cuttlefish camouflage themselves is even more intricate than scientists had initially believed.

Cephalopods, a group that includes creatures like cuttlefish, squid, and octopuses, have always been known as the ocean’s tricksters. Their extraordinary skill to shift their skin color and texture helps them disappear into their underwater environment.

A recent study published in Nature on 28th June takes a closer look at this complex phenomenon. Researchers from the Okinawa Institute of Science and Technology (OIST) and the Max Planck Institute for Brain Research have revealed the complex science behind the cuttlefish’s disguise.

How does cuttlefish camouflage work?

The cuttlefish employs millions of tiny skin pigment cells known as chromatophores to create a stunning array of skin patterns. Each chromatophore cell is encased within a muscular network. It is directly under the control of neurons in the brain.

These muscles contract and relax to expand or hide the pigment cell. Together, these cells act as biological pixels. These pixels create the intricate patterns on the cuttlefish’s skin.

“We used to think that cuttlefish used only a handful of pattern components to match their environment,” said Professor Sam Reiter, head of the Computational Neuroethology Unit at OIST.

“However, our latest findings indicate their camouflage is far more intricate and adaptable than previously understood.”

How researchers conducted the cuttlefish camouflage study

To uncover these astonishing findings, the researchers used an ultra-high-resolution camera setup to zoom in on the skin of the common European cuttlefish, or Sepia officinalis.

As the cuttlefish transitioned between different camouflage patterns, the team was able to capture the real-time expansion and contraction of tens to hundreds of thousands of chromatophores.

The team utilized a supercomputer at OIST to process data from about 200,000 skin pattern images. They applied a type of artificial intelligence, known as a neural network, to analyze various elements of the images. These included brightness, structure, shape, contrast, and even more complex image features.

“Each pattern was categorized and mapped onto a ‘skin pattern space,’ which represents the entire spectrum of skin patterns a cuttlefish can generate,” said Theodosia Woo, a graduate student at the Max Planck Institute for Brain Research.

“The cuttlefish doesn’t just detect the background and switch to a set pattern. Instead, they seem to constantly receive feedback about their skin pattern and use it to adjust their camouflage. We don’t yet know exactly how they get this feedback.”

Cuttlefish camouflage adapts in ways the human eye can’t detect

The researchers also noticed something unusual. Even when the same cuttlefish encountered the same background multiple times, the resulting skin patterns subtly differed in ways unnoticeable to the human eye.

Furthermore, the path the cuttlefish took to reach the final pattern was not direct. They transitioned through different patterns, pausing at each one, until they found the final result satisfactory.

“The cuttlefish would often overshoot their target skin pattern, pause, then come back,” Woo added. “This emphasizes the complexity of the cuttlefish’s behavior.”

Skin pattern display called blanching is equally mystifying

The team also examined another skin pattern display, known as blanching. This is a fast and direct response. It causes the cuttlefish to turn pale when threatened.

But some elements of the previous camouflage pattern remain. This suggests that information about the initial camouflage persists, even as the blanching response temporarily overrides it.

“Blanching might be controlled by a completely different neural circuit in the brain,” said Dr. Xitong Liang, a former researcher at the Max Planck Institute for Brain Research.

“The next step is to capture neural recordings from cuttlefish brains, so we can further understand exactly how they control their unique and fascinating skin patterning abilities.”

This fascinating research throws light on the intricate and sensitive mechanisms that cuttlefish, and perhaps other cephalopods, use to blend seamlessly with their environment. The results indicate that there is much more to learn about these masters of disguise.

More about cuttlefish

Cuttlefish are marine animals of the order Sepiida and are classified under the Cephalopoda class. This class also includes squids, octopuses, and nautiluses. Among invertebrates, they rank as some of the most intelligent and have particularly highly developed senses, especially vision.

Body structure

Their distinctive body structure includes a soft, oblong body and a unique, internal, porous shell known as a cuttlebone. The cuttlebone, composed primarily of aragonite, helps regulate the cuttlefish’s buoyancy, allowing it to hover at different depths in the water.

Cuttlefish have a pair of large, W-shaped pupils that give them an excellent field of vision and depth perception. Despite this, it’s believed that they are colorblind. This fact is very strange given their ability to change skin color with extreme precision.

Skin patterns and chromatophores

This brings us to perhaps the most fascinating feature of the cuttlefish: its skin. The cuttlefish skin is capable of amazing feats of transformation.

Using special pigment cells known as chromatophores, cuttlefish can rapidly change the color and pattern of their skin. This ability effectively allows them to ‘disappear’ into their surroundings. They also use this capability for communication and during hunting.

Diet and hunting

The diet of cuttlefish mainly consists of small mollusks, crabs, shrimp, fish, octopus, worms, and other cuttlefish. Their method of hunting is quite impressive; they use a pair of tentacles that shoot out to snag their prey.

Reproduction

When it comes to reproduction, cuttlefish exhibit intriguing behavior. Males will often guard their chosen female from rivals. They can even disguise themselves as females to sneak past other males.

Once fertilized, the female cuttlefish lays clusters of eggs and guards them until they hatch.

The lifespan of cuttlefish is relatively short, often not exceeding 1-2 years.

Cuttlefish produce ink

Another interesting aspect about cuttlefish is the ink they produce. Historically, artists and writers used this ink, known as sepia. Today, people often use it as a culinary additive for its color and flavor.

Cuttlefish have attracted the attention of researchers due to their complex behavior and advanced learning and problem-solving abilities. Their unique camouflage mechanism is of particular interest. Scientists hope that understanding it could lead to advanced technologies in the fields of material science, military tech, and clothing.

Overall, cuttlefish are complex and intelligent creatures that play a critical role in marine ecosystems. They continue to captivate researchers with their unique abilities and sophisticated behaviors.