“What is octopus ink made of?”

Photo by: Sharon Ang

Cephalopods (we’re talking octopi, squid and cuttlefish) are famous for gushing ink.  The behavior known as “inking” is simply meant to create an underwater smokescreen of sorts for purposes of escape.  When an octopus feels that it’s time to bail on a hungry predator, it squeezes out a gout of ink, sometimes accompanied by mucus (ew), and makes a quick getaway, leaving its would-be eater befuddled by the ink cloud.

But what is that stuff clouding the water, and is it useful for anything other than dramatic effect?

What’s in that stuff?

The ink that cephalopods squirt is made mostly of melanin – the same stuff that creates your skin tone.  The color varies slightly between species; octopus ink is blackest, squid ink is black with a blue tinge, and cuttlefish squirt brown.  Sadly, fuchsia and chartreuse are not in vogue for underwater squirting.

Another chemical present in the ink is tyrosinase, an enzyme which controls melanin production.  Tyrosinase, as well as some amino acids found in the ink, is thought to act as an irritant to some predators, acting as a kind of underwater tear gas.  It’s possible that this compound confuses the signals sent to chemically sensitive predators, like eels.  It may also simply mess up the olfactory signals coming into a smell-happy creature like a shark.  Think of it as the approximate equivalent of blowing a handful of hot pepper powder into your stalker’s face.

The ink has also been found to contain dopamine and dopa, likely functioning to alert other cephalopods to danger (i.e. octo-speak for “AAAhhh!   SHARK!”)

The whole business of how inking affects predators has not actually been scientifically researched all that much outside of anecdotal evidence, nor has the full significance of the ink’s chemical makeup been fully determined.  If you’d like to delve further into what’s known, there’s a more in-depth study of marine mollusk inking published here.

Whatever exactly is going on with the special potion that is octopus ink, it has been working just fine for cephalopods for millions of years without the need for tweaking – even 130-million-year-old ink is chemically the same as today’s (but a lot more dried out, like those ballpoint pens in the junk drawer.)

But wait, there’s more!

Now along with the ink cloud, a cephalopod may also cry havoc and let slip the mucus of escape.  The mucus blobs stick in the ink and hold shape longer than ink alone, creating confusingly cephalopod-sized blobs to draw predators to the wrong bite target.  Upon release of its dark mucus-y decoys, the cephalopod will often change its color into a lighter camouflage mode as it darts away.

Evolution being handy as it is, some deep-sea varieties have developed an ink alternative for use in the dark depths where a shadowy ink cloud would make no difference: they release a glowing cloud of luminescent chemicals.  Totally cool.

This, as well as using ink pigment to help camouflage eggs and using camouflage to mimic their own mucus/ink blob are some of the related neat tricks in an ink-wielder’s arsenal.

Yeah but what can it do for me?

If you’re directly encountering cephalopods, say while diving, probably the main thing ink is going to do for you is annoy you.  But, up here on land, there are a couple uses for the stuff, both age-old and up-and-coming.

In ancient times, cephalopod ink was used as a dye (the brown known as “sepia” got its name from the Greek word for cuttlefish).  Nowadays, squid ink especially is used as a dye in cooking (P.S. it’s harvested right from the ink sac, so no mucus gets mixed in, yay).

Medical applications are also in the works.  Chemicals in the ink are toxic to some kinds of cells, including tumor cells and some germs, so perhaps there is a future in disease-fighting ink-based medicines.  As for the here and now, cuttlefish ink has been used to create the anodes on prototype edible batteries, which are anticipated to be useful for internal medical monitoring and drug delivery.

“Remember, Dear, to take your cuttlefish battery with your breakfast!”

What if I could have mutant octopus inking abilities?

Let us envision how the approximate anatomical layout and environmental effect of inking would play out with a human, because, why not?  In your new role as The Human Inkomatic, you would have an ink sac taking up space in your abdomen, with a release chute exiting at your nethers.  Your defense would cloud the vision and irritate the other senses of attackers while confusing them by creating a decoy while also alerting others of your species to the danger at hand.  Thus I would imagine you could blow out a large smoke screen containing an inflatable faux human alongside some tear gas with a sound like someone yelling “fire!”

That would be quite the mutant power.  Honestly, though, if I got to choose an octopus feature to be my mutant power, I would give inking a miss and rather go for the ability to fit through very small holes or, better yet, the octopus’ remarkable camouflage ability.  Or maybe take the cephalopod’s ability to communicate by color-changing its skin.  I wonder what my freckles would have to say?

OK, one more video link, because these creatures are just so cool!