Octopuses—yes, that is an appropriate plural—are some of the most beautiful,
mysterious, and absurdly intelligent creatures on this planet.
They can change color. They can change shape and texture. They strategize, play, and solve
puzzles. They've got three hearts, their skin can see, their blood is blue, their magic
trick is disappearing, and over half of their brain is not in their head. Instead, it’s
in these things. No, they’re not tentacles. They’re arms!
And because they’re some of the most fascinating arms in the animal kingdom, today, we’re
gonna wrestle with those.
So, first, a quick taxonomic rundown. In the
cephalopoda class, you’ve got squid, octopuses, and cuttlefish. Cephalopod literally means
“head foot” in Greek, and I mean, it kinda works.
Octopuses are a bit different from other cephalopods: squid and cuttlefish actually do have tentacles.
Two of those bad boys, specifically, which they use for hunting. Tentacles are often
longer and kinda slimy, with suckers or hooks at their tips.
All those other lanky limbs are arms, used for grappling, grasping, galloping, and generally
getting up to mischief. The first thing it’s important to know about
octopus arms is that they can think on their own. While that might not sound too surprising
when it comes to the third-right arm that, incidentally, functions like a penis, it’s
a complete departure from how most animals that we consider “intelligent” operate.
Look at your hand. Before you pick up a snack, you think about it. And then your hangry brain
sends messages through your spinal cord to your hand, and your fingertips use their few
hundred mechanical receptors to achieve the task.
Now, if you were an octopus, your fingers would first find the snack, sniff it, decide
if it’s worth your time, and grab ahold of it, and then, maybe, be kind enough to inform
your brain about the entire thing. Well, the rest of your brain, that is.
See, about two thirds of what we call an octopus’s “brain,” or its neurons at least, are
located in its eight arms. For them, this means “thinking” is a full-body experience.
Compared to those few hundred mechanical receptors in your fingertip, each sucker on an octopus
has tens of thousands of both chemical and mechanical receptors. This means that
they can essentially taste an object as well as feel its texture and weight, and decide
what to do with it without waiting for a command from the central brain.
While the amount varies, the average number of suckers on each arm is over two hundred.
So, do a little math and that’s hundreds of millions of sensory cells to explore the world.
That’s a lot of information! Each sucker is made of two regions: the disk-like
part you can see is the infundibulum, while the center cavity is called the acetabulum.
When an octopus reaches for something, the infundibulum will flatten to feel the surface first.
The octopus uses its sucker’s acetabulum to attach to the object,
with a combination of radial and
meridional muscles and tiny hairs that maintain the connection like velcro.
This makes the animal’s grip so strong that the largest suckers out there can lift about
one Dolores worth of weight… each. And oh, um, did I mention their arms can regenerate, too?
With all of their incredible abilities, humans
are looking to octopuses to not only better understand intelligence and consciousness,
but to inspire innovations in materials science, medicine, and especially, soft robotics.
There's so many challenging questions in the engineering side that we don't know the answers.
Nature has already figured it out. So, in particular, regarding octopus, they've
got eight arms, of course. Think about each of these arms have technically infinite
degrees of freedom. And controlling even a single arm with so many degrees of freedom
is a very challenging task for us as engineers. That’s why Hamid and his team are working
on developing robots made of hydrogel, which mimic the structure of an octopus’ arm.
The interesting thing about hydrogel is you can make it so that it responds to light,
mechanical, electrical and chemical stimulation, just like an octopus. And then what
we proposed was to 3D print the entire structure using hydrogel, in one shot, with embedded
neurons made of silver.
If they’re successful, this octo-bot could make huge strides in fields from manufacturing
to medicine. Think sensitive, flexible machines that could assist with assembly or surgery.
So, let’s take care of our oceans today to make sure they’re healthy for generations
to come. Because with so many incredible, strange creatures with such amazing capabilities,
who knows where the mysteries of the deep will take us next?
Thanks for joining us for this first season of Tusks to Tails. Keep coming back to Seeker
for all your science deep-dives, and we’ll see you next time!