Why do squid release ink?

Since scientists began studying squid, they’ve been trying to understand why squids release ink. Could squid ink be used to attract a mate, repel predators or confuse prey? Up next Science Friday takes us inside the lab at the Monterey Aquarium Research Institute in California where scientist Stephanie Bush searches for these answers.

TRANSCRIPT

Since scientists began studying squid, they've been trying to understand why squid release ink.

Could squid ink be used to attract a mate, repel predators, or confuse prey?

Up next, 'Science Friday' takes us inside the lab at the Monterey Bay Aquarium Research Institute in California, where scientist Stephanie Bush searches for these answers.

My nickname is Dr. Steph-lopod.

Should I do this, too?

We're in the necropiscatorium at MBARI.

It actually means the dead fish room.

So this is Taonius.

It just says squid and then, in parentheses, vicious.

For as long as we've been studying squid, we've known that they release ink.

But in that whole time, we thought that the ink was simply a visual defense.

But we've hypothesized that there's actually additional uses for squid releasing ink.

And it would be great if we could set up an experiment in a giant tank that replicates the conditions of the deep sea and put some squid in there.

But that's currently not an option.

One of the first things we thought of is, 'Maybe the ink contains chemicals that are repellent to a potential predator.'

If you're a predator swimming through the ocean and you run into this bad-tasting thing, you might stop for a second and kind of, you know, shake your head and try and get rid of that from your olfactory system.

And, in the meantime, the squid is getting away.

Then there's the other side of that, equally possible.

The ink just smells like squid.

And that is actually an attractant.

So the predator is out to find squid, to eat it.

So if they come across some ink, and that ink smells like squid, they're like, 'Ooh, I'm close.'

That could distract them for long enough that the actual squid gets away.

It could be a possibility that a squid would use ink to attract a mate.

The deep sea is a huge habitat, and it's completely dark.

And you don't necessarily want to be swimming around all the time, potentially bumping into predators, when you're trying to find a mate.

A low release of a few puffs of ink, and, as the ink dissipates, another squid might sense that ink and know, 'Okay. I should, you know, look around a little bit more.'

You can think of it as the lazy man's way of attracting a mate.

One of the coolest things that has been found recently by some Japanese researchers is that there's a species of pygmy squid that actually release ink as they're hunting.

So they'll release a few puffs of ink and then swim through those puffs of ink and grab prey.

So it's a visual distraction from their prey instead of their predators.

Some gnarliness.

Oh, that looks disgusting.

This is nasty.

Actually, these ones look pretty cool.

The one on the right is Taonius.

And the one on the left is Galiteuthis.

There are hundreds of species of squid, and all of them that have been studied release ink.

One of the core tenets of science is to continue questioning the things that we know and the things that we think we know.

We want to constantly challenge the, sort of, firmly held beliefs that we have in science.