Incredible Ink: Defense Mechanism, Food Source, Medicine & More

Fall 2020 Curiosity Box - Inq's Pen Holder

Just to refresh your memory, the cephalopod family has four creatures in it: octopus, squid, cuttlefish, and their distant cousin the nautilus. Aside from their eight arms and squishy bodies, the first three members of the family are known for the production of ink, which they use to distract and fight off predators. The colors in the ink come from melanin, the same organic pigment found in human hair, and like all good pen sets, they come in an array of colors! Octopus ink is the blackest, squid ink is a bluish-black, and cuttlefish ink is a reddish-brown.

 

Speaking of which, cuttlefish ink may be more familiar to you under another moniker, which is taken from the species’ scientific name: sepiida. Yup, it’s sepia!  Cuttlefish ink has been used since the time of the ancient Greeks by writers and artists, most famously Leonardo da Vinci – look at his notebooks to get an idea of what the sepia ink looks like. Your camera or smartphone may even have a filter called “sepia” to mimic the color of old-time photographs, which used sepia toning to give a warmer feel to black and white images, and chemically prevent them from fading quickly.

 

But we don’t just look at ceph ink – we also eat it!  When you go to fancier grocery stores or Italian restaurants, you may see “squid ink” pasta, which actually does contain cephalopod ink, though is much more likely to be from the cuttlefish. According to Italian cooks, as far as flavorings go, cuttlefish ink is “mellow, velvety, [&] warm,” while squid ink is smellier and harsher. Other dishes, like Japanese ikasumi jiru and Spanish Arròs negre (squid ink paella), really do contain squid ink.

 

It’s not just food, either: people in ancient Greece, Egypt, and China used the inks to relieve a variety of illnesses. Modern medical studies have also shown an array of anti-tumor and anti-cancer effects. Enzymes made from purified squid ink have also been shown to dilute blood vessels, making them a possible hypertension treatment, and studies show that both squid and cuttlefish ink have anti-retroviral properties. One of the great things about ceph ink as a medicine is that there’s a lot of it; the ink sacs are a byproduct of the over 3 million metric tons of squids, octopuses, and cuttlefish caught for food and other human uses.

 

That’s how humans use cephalopod ink – what about the squids, octopuses, and cuttlefish? Ink evolved as a defense mechanism against predators, but it’s more than just shooting out a giant ink smokescreen and scooting away (though they do that); it’s a complex chemical weapon for use in the unforgiving world of the sea. The ink contains the enzyme tyrosinase, which can confuse a predator’s sense of smell and taste. It’s also got neurotransmitters like dopamine, which when detected by other cephs in the area, alerts them that a predator who hunts their kind has been nearby!

 

Perhaps strangest of all, some cephalopods combine their ink with mucus to make a “pseudomorph,” a duplicate copy of themselves that appears to be the original animal, especially when seen through the haze of a larger ink cloud. When attacked, the ceph drops a pseudomorph, then jets away, leaving the inky doppelganger behind to be chomped on by a frustrated predator. To further assist in the ruse, they also instantly change color (another ceph superpower) to blend into the sea, leaving the darker, easily targeted pseudomorph behind. Scientists have a name for this tactic: “the Blanch-Ink-Jet Maneuver.” It’d be cool if humans could do this too, though you’d need to carry around a mannequin and a jetpack, so…okay, maybe it’s not that practical.

 

So there you have it: a sophisticated defense mechanism for cephalopods, an art supply, food source, and medicine for humans. More than just a filling for magic markers, it’s the incredible cephalopod ink!