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SARAH MCANULTY: I think you have to be nuts to not think
a bobtail squid is cute.
Those big black eyes, I think they're just the cutest things
ever.
[SPARKLE SOUND]
But Hawaiian bobtail squid are basically the couch potatoes
of the cephalopod world.
They sit in the sand for much of their lives.
They do occasionally get up to hunt.
But they're effectively relaxing on vacation in Hawaii.
My name is Sarah McAnulty, and I'm a squid biologist.
I study the symbiosis between Hawaiian bobtail squid
and their beneficial bioluminescent bacterial
partner.
A bobtail squid is a small squid that
lives off the coast of Hawaii.
They're nocturnal, and they're about the size of a lime.
[SPARKLE SOUND]
So these squid swim around at night.
And it's basically like the squid
has a constantly glowing light bulb situated
sort of in the center of the squid's body on the underside.
And that light bulb is all chalked full of bacteria
called vibrio fischeri.
If you're a cephalopod, you're super easy to eat.
You're basically like assuming protein bar.
[MUNCH]
So you have to be very good at camouflaging.
Typically, if this squid wasn't glowing,
it would look like a little squid-shaped shadow
or silhouette.
With the help of the bacteria, they've
matched the moonlight precisely coming down from above.
That partnership is called symbiosis.
The bacteria gets a place to live,
and if you're a squid, from the bacteria
you get light as camouflage.
Now, in terms of how the bacteria get
in to the light organ, this is a really cool process.
They go through this molecular gauntlet.
The squid is constantly beating cilia
in the opposite direction of where
the bacteria needs to swim.
So these bacteria need to be awesome swimmers,
and they also need to be able to put up
with a lot of, basically, insults from the squid.
You've got nitric oxide.
You've got acid.
But this vibrio fischeri is able to eventually swim actively
down pores and ducts into the depths of the light organ.
And we call that deep area where the bacteria
are trying to get to the crypt.
And once they're there, the immune cells
also play a role in this specific symbiosis.
My work is trying to understand how immune cells, which
we call hemocytes, are able to tell
the difference between beneficial bacteria and others.
So I've developed a test and a method
for watching the behavior of hemocytes.
The way I do this is I take a squid from downstairs
in the squid room and I anesthetize it using ethanol.
[MUSIC BOX LULLABY]
It knocks them out completely.
And I do a blood draw.
I only take out a tiny drop of blood from these little squid.
And then I'll do what I call squid PR, which
is just like CPR on a squid.
I'll blow water over their gills using a pipette.
I'll tap them a little bit.
And they burst back into life with color.
So we take the blood out of the squid.
And then we stain the immune cells with a dye.
So we have bacteria in one color,
and then we have a different type of bacteria
in another color.
And then we have the immune cells in far-red.
We look at these different colors to tell who's who.
And then I take time lapse videos of these different cell
types all interacting.
When the immune cell finds a bad bacteria in this context,
it just engulfs and eats and kills it.
But with vibrio fischeri, it will bind, maybe carry it
around for a little while.
And then it just sort of leaves it behind.
So we think that there's some kind of education process
that occurs between the bacteria and the squid
at the beginning of the squid's life
to teach the immune cells that vibrio fischeri is
the beneficial bacteria.
The immune cells will migrate into the crypts
where the bacteria live at night.
And they will basically sacrifice themselves
to feed the bacteria.
This is totally nuts and super cool
because normally you would think of an immune cell
as being just a destroyer, not as something
that would be feeding bacteria, of all things.
But this group found that this is what's going on.
The bacteria in the squid have been living together so long
that they've both adapted to helping each other
and being the perfect life partners.
It may seem bizarre.
But it's really important because these squid are giving
us a really unique opportunity to understand
how animals and bacteria relate and how
the colonization by bacteria affects
your whole immune system, affects your whole genome,
and what far reaching parts of the body
are affected by having beneficial bacteria live
in you.
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