Thanks to the Monterey Bay Aquarium and their research
and technology partner MBARI for partnering with us on this episode of SciShow.
They worked together on an exhibition, “Into The Deep:
Exploring Our Undiscovered Ocean,” to give visitors to the Aquarium a rare look at
some of the animals that thrive in the
least-explored area of the planet, the deep sea!
[♪ INTRO]
Imagine you are a swimming animal stuck in a
never ending game of The Floor is Lava.
You spend your entire life moving through the water,
never touching the ocean floor.
Chances are, you’d get pretty good at swimming!
Well that is exactly what the life of a gossamer worm is like.
And their swimming isn’t just efficient and elegant.
It could help researchers develop the next great marine robots.
Gossamer worms are holopelagic, which means that they
live their whole lives in the water column, that area above the ocean floor.
These peanut-sized, gelatinous sea worms are part of a group of
segmented marine worms called polychaetes.
But unlike many of their wiggling underwater cousins,
gossamer worms lack two of the key defining features of polychaetes.
The word polychaete means ‘many bristles’,
because almost all species in this group have bundles of tough,
brush-like spines called chaetae at the ends of their little feet.
That is, except gossamer worms.
Their feet are naked.
Gossamer worms also don’t have septa,
thin bands of tissue that give worms their segmented, bubbled look.
Gossamer worm bodies look more like a cross between
a balloon animal and a fern frond.
And those differences are more than just aesthetic.
It means gossamer worms move in a
totally unique and downright mesmerizing way.
It’s like a combination of slithering side to side and spirit fingers.
See, gossamer worms have thirteen or more pairs of parapodia:
little feet that look a bit like paddles.
And each parapodium moves like an oar through the water.
But unlike oars of a rowing boat, those feet don’t all stroke at the same time.
They move in a beautiful pattern called metachronal paddling,
kind of like a wave rippling through a crowd at a football game.
And, at the same time, the worms also wiggle their flexible,
fluid-filled bodies from side to side in what’s called a body wave.
Their unique swimming style makes them
the perfect subjects for studying underwater movement.
And that’s just what scientists from MBARI,
the Monterey Bay Aquarium Research Institute, have done.
They went out into the deep ocean and, using a remotely operated
underwater vehicle, sucked up several gossamer worms to study.
Then they filmed the worms using high speed cameras
as they swam around in transparent tanks, both at sea and back on land.
Using digital markings on different points on the worms’ bodies,
the researchers saw that each movement of the parapodia
had a power stroke and a recovery stroke.
The power stroke pushes the animal forward,
and the longer recovery stroke brings the legs
back into their starting position, ready for the next push.
And, by shining a laser on the worms, researchers could see how the worms have
optimized their swimming motion to increase thrust in the power stroke,
and reduce drag in the recovery stroke.
During the power stroke, the parapodia lengthen before they swish
through the water, helping them increase thrust and drive them forward.
And during recovery, the parapodia contract again,
reducing drag so that the parapodium glides through the water.
And there was one more piece to this fancy footwork puzzle.
When researchers slowed the videos down,
they noticed that the two fleshy ends of each parapodium, called rami,
would spread out as the worms pushed themselves forward
and then contract again during recovery.
By spreading their toe-like rami, the worms could increase the foot’s surface area,
once again increasing thrust and giving them more power.
But metachronal paddling isn’t the only thing
helping gossamer worms dance through the water.
Using mathematical models, researchers figured out that the body wave
isn’t doing much on its own to help the animals swim.
Only about a third of the swimming speed comes from it.
Instead, the body wave amplifies the thrust of each of those little feet.
On the one hand, or on the one foot, it gives each paddling foot
room to angle itself further forward and then end up further back.
That means the angle each leg can
make relative to the body is bigger, resulting in more thrust.
Second, the timing of the body wave and the foot paddling is synced so that
the feet are far out from the body when they’re
doing their power stroke, for maximum efficiency.
Now, unpacking the details of how these elegant creatures swim is helpful
for understanding how they spend literally their entire lives paddling along.
But it could also help inspire new ways for robots or vehicles to swim underwater.
For example, the researchers propose that you could make the propellers of
an underwater craft more flexible, to mimic the gossamer worms’ paddle feet.
Or, engineers could try and make the body of the robot flexible
to simulate the way the gossamer worm sways side to side.
That might be a bit trickier, given the whole thing has to be watertight and all.
But it might just start out as dividing the body up into smaller, rigid sections.
Kind of like those wiggly snake toys you had as a kid.
And who knows, those new underwater robots could help scientists explore
more of the deep ocean, take scientific measurements, search for
sunken objects… and even, find other awesome organisms
like the gossamer worm.
We teamed up with Monterey Bay Aquarium and MBARI to bring you this episode!
They are super excited for folks to learn about the deep sea.
You can make like a gossamer worm and
paddle on over to their websites and social media.
MBARI’s YouTube channel has awesome videos about the deep sea,
and on the Aquarium’s website, you can make a donation to support their exhibits,
education programs, and ocean conservation work.
And also, the Aquarium’s YouTube channel posts these, like,
amazing lofi mixes set to relaxing Aquarium videos that are perfect for
getting your work done, if you need somewhere to go after this!
[♪ OUTRO]