What is it like to be a cuttlefish?

There is perhaps no animal known to humankind to be more precious and cute than Sepia officinalis.

a.k.a. Cuttlefish!

Aren’t they precious? (◕‿◕)♡

But the cuttlefish is more than a pretty thing to look at. Having a large and complex nervous system, the cuttlefish is considered one of the most intelligent creatures on the planet.

Despite its name, the cuttlefish is actually not a fish. It is a relative to octopus, but more closely related to squid. These three animals—octopus, squid, and cuttlefish—are part of a larger family of marine mollusks called cephalopods, ancient animals that have been wandering the ocean for over 500 million years.

Found predominantly in shallow, coastal waters throughout the world, the cuttlefish spans anywhere from 20 to 35 inches and can weigh up to 11 lbs. To swim, it has two fins spanning the length of its body, and it can propel itself by shooting water from its gut. At the front of the cuttlefish are eight tentacles and a beak, which it uses to crack open the shells of crabs and other crustaceans. Cuttlefish also have two longer tentacles, with a single suction cup at each tip, and these tentacles can elongate to grab prey.

Cuttlefish, like other cephalopods, also have sophisticated eyes. Shaped like a smooth, curved W, the cuttlefish’s eyes can perceive the polarization of light and have no blind spots.

A master of camouflage

The cuttlefish is perhaps most well known as a master of camouflage. It can skip around colors in a mesmerizing display. It can also change skin color in less than one second, as well as make its skin shimmer light to “hypnotize” prey.

To camouflage itself, the cuttlefish can contract small muscles around tiny, coloured skin cells called chromatophores. The cuttlefish has thousands of these tiny cells scattered throughout its skin, and these are controlled directly by the central nervous system, which is why it can change so fast. By gently flexing the muscles around the chromatophores, the cuttlefish releases pigment into the outer layer of its skin, allowing it to control its coloration and body pattern to emulate virtually any surroundings and thereby hide in plain sight.

Though chromatophores, the cuttlefish can produce colors no matter how strange and has been caught spinning through colors like a kaleidoscope.

The cuttlefish’s color-changing skills have been useful for the creature not only for hunting and hiding, but perhaps most importantly—communication. To communicate, the cuttlefish can catch the attention of other cuttlefish through vivid color shows, reshaping its body, and producing complex lines and textures on its skin.

In a November 2002 study published by the National Institute of Health, three researchers explained how the cuttlefish camouflage and communicate with each other through skin color. Although more research has to be done, the researchers said, the cuttlefish is thought to have a sophisticated language of communication.

By watching groups of cuttlefish over several months and recording common patterns, the researchers identified and classified 13 distinct body patterns used by the cuttlefish to communicate. The way the cuttlefish make these particular body patterns is quite unusual, such as small white triangles on a fin, turning its skin from smooth to coarse, and splaying or waving its arms. The researchers watched as the cuttlefish switched through these various body patterns to talk with other cuttlefish, such as by rapidly changing textures and colors, as well as waving its fins.

It’s quite fun to watch, because the cuttlefish’s intelligence is on full display. It’s also a beautiful demonstration of the cuttlefish’s talents with color.

A fact that makes absolutely no sense

Now we have to approach a fact about cuttlefish that is by far the most surprising, given everything we know about the animal’s unique abilities with color. Numerous scientific studies have shown that cuttlefish are, in almost all cases, colorblind.

It makes almost no sense, but yet both anotomical and behavioral evidence points to this fascinating conclusion. Unlike the human eye that has several types of photoreceptors to distinguish color, the cuttlefish’s eye, biologists discovered, has only one type of photoreceptor in it. In short, there’s almost no chance that the cuttlefish can make out the difference between similar hues of color.

Since scientists have made this discovery, researchers have been fascinated with the cuttlefish’s confusing relationship with color. Specifically, scientists wonder, how does the cuttlefish blend seamlessly into its colorful surroundings with no access to color vision?

Although scientists still don’t have an answer to this question, a leading theory among biologists is that cephalopods can change skin color without input from their brain or eyes. Yes, researchers suggest that the cephalopod skin has the capability to intrinsically handle visual information and respond to it.

Let me explain: In a May 2015 study published in the Journal of Experimental Biology, evolutionary biologists Desmond Ramirez and Todd Oakley put forward crucial evidence to show how cuttlefish, and cephalopods in general, can match the vivid colors in its surroundings almost perfectly in a matter of seconds through sensory mechanisms within its skin.

First, the researchers showed how a particular species of octopus—Octopus bimaculoides, a relative of the cuttlefish—have skin cells active with what’s called ‘light-activated chromatophore expansion,’ known simply as LACE. The researchers wanted to see how the skin would react under light across the visible light spectrum, from violet to orange. They also wanted to see how the skin reacted under white light.

By putting the octopus’s skin under various hues of lights, the researchers found that the octopus had unique responses depending on the color’s hue. Because of LACE, researchers discovered, the octopus’s skin could not only detect light, but it could also produce a response affecting the skin’s color. This means that the octopus’s skin, or some other connected organ, handled neurological response at an immediate level.

While this evidence is a positive step toward understanding the cuttlefish’s camouflage skills, researchers Ramirez and Oakley note in their study that their results should be taken lightly because there have not been studies specifically on cuttlefish. 

Still, the possibility of the cuttlefish being capable of handling immense amounts of visual sensory input through its skin is exciting for scientists. It raises new questions about the cuttlefish’s sensory mechanisms, as well as the cuttlefish’s intelligence.

Peter Godfrey-Smith, science writer and philosopher, said these particular findings into the cuttlefish’s skin and color-changing abilities elicits more questions about the creature’s neurology and fundamental biology.

“We don’t yet know whether the skin’s sensing is communicated to the brain, or whether the information remains local,” Godfrey-Smith said in his book Other Minds: The Octopus, The Sea, and the Deep Origins of Consciousness. “Both possibilities stretch the imagination. If the skin’s sensing is carried to the brain, then the animal’s visual sensitivity would extend in all directions, beyond where the eyes can reach. If the skin’s sensing does not reach the brain, then each arm might see for itself, and keep what it sees to itself.”

A short life

The cuttlefish is one of the smartest creatures in the sea, yet its lifespan is one of the shortest, living at most one to two years.

When the cuttlefish is five months old, it begins the mating process through an elaborate ritual held every Spring. Male cuttlefish compete in a show of dominance in front of the female cuttlefish, and the female cuttlefish choose the most impressive males to reproduce with them. If a male cuttlefish is too small to attract a female cuttlefish in a mating season, it usually participates in the next year’s mating system with more success, often because the cuttlefish is an indeterminate grower.

After reproducing, the cuttlefish begins an aging process and enters its final stage of life. 

Even knowing its short life, scientists continue to research the cuttlefish because to know what it’s like to be a cuttlefish might help us answer fundamental questions about ourselves.

According to Jean Boal, an associate professor of biology at Millersville University in Pennsylvania, by understanding intelligence in the cuttlefish, we can understand intelligence in humans.

“What’s really exciting about cephalopod intelligence is, we know that their relatives are clams and snails,” Boal said in a PBS interview. “Those are not animals that had a need for great intelligence, so whatever happened to cephalopods was different. If we can figure out what they’re using their intelligence for, that would tell us what these factors are in the environment that created need for intelligence. And that can shed some light on our own intelligence.”