Majestic, Underwater Freaks of Nature: Cuttlefish

Cuttlefish and other Cephalopods: Marine Magicians

When I was just an awkward little eight year old, I watched a NOVA documentary on cuttlefish. From the first minute the camera zoomed in, I was blown away by these stunning members of the Mollusca phylum. Especially to us landlubbers, the cuttlefish and other members of the Cephalopod class look like something out of a science fiction movie, but the structure of their anatomy is even more interesting.

Metasepia pfefferi, a.k.a. Flamboyant Cuttlefish are one of the smallest known species of cuttlefish, growing to a maximum 8cm in length.

Sepia apama a.k.a Giant Cuttlefish are the largest of their species and can grow to 50cm in length.

Most people seem to know that other members of the Cephalopod class such as squid and octopus can release ink from their ink sacs when startled. Like a magician's smokescreen, this dark cloud allows a Cephalopod to slip away from a predator. Cuttlefish and certain other Cephalopods can also take this illusion even further by mixing a little extra mucus into the ink to create a pseudomorph. This is a decoy roughly the same size as the creature that emits the ink. Predators, including humans, have been known to accidentally pursue a pseudomorph instead of their Cephalopod prey.


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This is a squid using a pseudomorph to escape.

Similarly, many Cephalopods can camouflage themselves by changing their skin color. The mechanism behind this adaptation is not entirely understood by scientists. The general idea is that cuttlefish, for example, have layers of pigment sacs known as chromatophores underneath their skin that expand and contract in response to neuron signaling.

Figure 4: Can you spot the cuttlefish hiding in this photo?

Cuttlefish can take camouflage up a notch by changing the texture of their skin as well as the color. By contracting circular muscles, cuttlefish can become lumpy, spiky, or bumpy in order to better blend in with their environment.

To see (or not to see) some cuttlefish in action, check out this video.

Another way some cuttlefish use their color-changing abilities is to stupefy prey. By rapidly changing color, cuttlefish can essentially hypnotize their targets into staying still just long enough to be eaten. This hypnotic technique resembles a continuous black and white spiral optical illusion. Don't believe me? Check out this National Geographic video.

Hypnotic Spiral Trance


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Cuttlefish hypnosis attack

Decoys, illusions, hypnosis? What more can you ask from the unending magic show that is cuttlefish?

Cuttlefish are under extremely strong selective pressure because they are essentially blobs of tender meat floating around in the ocean without shells or spikes like some other members of the Mollusca phylum. Cuttlefish have evolved to be masters of disguise rather than armored or fierce.