How octopuses battle each other

Them's fighting words if you're an octopus, in that more than one octopus in a space often means a rumble. Our intrepid neuroscientists analyze aggression by observing the fighting behavior of two-spotted octopuses or, if you prefer, octopodes.

Greg Gage: The octopus is
a rather strange-looking animal

that exhibits amazingly complex behaviors.

They have the most impressive nervous
system in the entire invertebrate world.

They have about a half a billion neurons

that are distributed
throughout their body,

such that two-thirds of the neurons
are actually in its legs.

Now mix this in with camouflaging cells,
jet propulsion and a razor-sharp beak,

and you have all the makings
of a formidable predator.

And then throw in the fact
that the octopus is a solitary creature,

and suddenly, we have ourselves
a real cephalopod fight.

(Bell)

[DIY Neuroscience]

We know that almost all animals fight --
for food, for territory, for mates.

The octopus is no different,
and knowing their fighting behavior

could help us better understand
these fascinating creatures

and how they interact.

My friend Ilya has been observing
the classic fighting behavior

between California two-spot octopuses.

Ilya Chugunov: Most people
think that it's "octopi,"

but that's actually incorrect.

The correct plurals
are either "octopuses" or "octopodes"

if you want to be very Greek about it.

GG: So how do you do your experiment?

IC: First, I like to set up
the chamber just so it's ready,

so I get a jug of water,
I aerate it by shaking the jug.

It seems that if the water is
well-aerated, they're a lot more active.

This gives the octopuses
some room to breathe.

I get the first octopus --

Here, buddy. Here, pal.

Put it in, set up my GoPro,

put the second octopus in,
cover it up and leave it alone.

(Bell ringing)

Rule 1: There's always
an aggressor.

There's always one octopus
on defense, one on offense.

Usually the one that's taking up
more space, that's more boastful,

definitely the aggressor,
most likely the winner of the fight.

The loser's pretty obvious.

They get pushed around,
they curl up, hide in a corner.

A lot of the time,
when there's initial contact,

if one of them is too much
on the defensive side,

the second one will sort of poke at it,
grab at its tentacle and see,

"Hey, do you want to fight me,
do you want to turn around?

Do you want to start a wrestling match?"

So it'll just poke and run away.
Come back, poke and run away.

(Bell ringing)

Rule 2: Avoid eye contact.

When the octopuses come
towards each other to begin the fight,

they don't actually face each other.

They approach sideways.

The defensive octopus
tries to face away from the attacker

until it's the critical moment
it knows there's no way to avoid a fight.

GG: Really, the one who's waiting
to the last moment

is the defensive octopus.

(Bell ringing)

Rule 3: Flash your colors.

The aggressor in a fight will quickly
and sharply flash bright black on his arms

when he's about to initiate a fight.

(Bell ringing)

GG: Ooh, and already --

IC: We're seeing some action.

Looks like they've spotted each other.

GG: Right. So now he's going to come --
He's approaching, but not directly at him.

IC: Yeah, they're like
almost completely antiparallel.

GG: And then right there --

IC: Yeah. They contact,
and then their arms clash together.

(String music)

GG: So we've taken the first steps
in understanding fighting in the octopus.

And you might be asking yourself:
Why does this even matter?

Well, these types of curiosity-based
research questions can often lead

to some unexpected
insights and discoveries.

We've learned a lot about ourselves
from studying marine animals.

Squid have taught us
about how our neurons communicate,

and the horseshoe crab
has taught us about how our eyes work.

So it's not too far of a stretch to say
that some of these behaviors

that we're seeing in the California
two-spot octopus are similar to ours.