- Despite their very poor monochromatic vision,
cleaner shrimp maintain cleaning stations
identify fish that want to be cleaned
and even clean fish that would normally eat crustaceans
the size of the shrimp.
So how does it work?
How do fish identify that that shrimp
is a cleaner shrimp rather than a meal?
Hey guys and girls, I am ReefMan,
and this week we'll be answering those questions and more,
we'll be talking about a paper titled
mutual visual signaling
between the cleaner shrimp, Ancylomenes pedersoni
its client fish.
Sorry for the Latin, that paper was published
by the Royal Society Publishing back in 2018.
There's also a second paper
that we'll be using in this video.
And that one is specifically
about the differences in cleaner shrimp behavior
when you're dealing with a predatory
versus a non-predatory fish.
And both of those
of course are linked down below in the description,
so if you want to check them out
that's where the link is.
Also, thanks for the authors
providing the awesome videos that are gonna be showing
throughout this video.
In nature for signals to arise and work,
well, they need to be consistent over time
and they need to result in a boost
for both the signaler and the receiver.
In cleaner shrimp, which maintain those cleaning stations
on coral reefs all around the world,
both the shrimp and the fish benefit.
The shrimp receives a meal made of ectoparasites
and dead tissue and things like that.
The fish is freed from all those maladies.
The shrimp should also signal to advertise
that they're cleaners, not food.
And that signaling will probably,
well it should be most intense when the client fish
is a fish that might otherwise eat the shrimp.
And we do see that in Lysmata amboinensis,
one of the most commonly kept cleaner shrimp,
the skunk cleaner shrimp,
which rocks its front legs from side to side.
And that's done way more often when the fish
right in front of the shrimp is a predator
versus when it is something that wouldn't eat the shrimp.
The Pederson's shrimp, which is the species you see
in the videos throughout this video,
it doesn't use its legs.
Instead it whips its bright white antenna around
to signal its cleaning services to clients,
but what's really going on there?
That's what the authors of this paper
were trying to find out.
It could be that they're moving their antenna around
in order to just smell the water,
check out what's around them instead of
to advertise their services or maybe something else.
Shrimp also have very poor eyesight.
They actually only see in one color.
It's kind of a greenish color
and they have very poor resolution.
You can see how bad their eyesight actually is.
Hardly being able to even make out a fish that's right
in front of them.
To help with this, fish looking for cleaning services
often change color while hovering motionless
near the shrimp's cleaning station.
By turning to a dark color, the fish stand
out better for the shrimp to be able to see them.
This was also something that the authors wanted to
investigate, as this was just a hypothesis
that had yet to be proven at that point.
So they set up GoPro cameras, one looking down
and one looking from the side towards the cleaning stations
and they've recorded over a hundred hours of footage.
From that footage, they noted the interactions and behaviors
that took place in those cleaning stations.
They found that those behaviors broke down
into just a few different types.
Posing, where the client fish is just motionless,
waiting for cleaning, color changes,
both darker and lighter.
Jolting, probably when a cleaner
is just a bit too aggressive
and antenna whipping, which we talked about before.
And obviously of course, cleaning.
By mapping all of the interactions that they saw
in the videos, the team was able to develop
a network diagram of those interactions
and how often they play out in a certain order.
Most commonly the shrimp whips its antenna
and then the fish poses,
and then either cleaning begins
or if not, the fish would turn to a darker color
leading to cleaning.
Antenna whipping at the beginning,
predicted cleaning behavior 82% of the time.
To find out if any scent was involved,
they used an iPad placed up against the aquarium
just displaying various images and videos.
There could be no scent involved here.
The iPad it's inanimate and it's not even in the tank.
And yet the shrimp displayed antenna whips
and even touched the tank's walls
where the images were on the iPad.
So from that, we're pretty confident
that the antenna emotion is not related
to just trying to get a good olfactory smell of the area.
An overall darkening of the client fish
does seem to desire or indicate a desire to be cleaned.
When posing alone isn't enough,
changing to a darker coloration resulted in cleaning 47%
of the time, nearly tripled their overall original chances.
Because it doesn't happen after the shrimp
is already being cleaned,
we can be confident that this is actually a signal
from the fish to the shrimp asking
for those cleaning services.
It might help the shrimp see the fish
maybe making them stand out a bit more
against the background of the reef.
Antenna whipping is a reliable signal from the shrimp
that they're open for business.
On the other species of shrimp,
the skunk cleaner shrimp, rocking their front legs
back and forth, performed this function.
And you'll actually see that in your own tank
when you're cleaning near the shrimp
if you've got one of those in your tank.
Antenna whipping was often followed
by the client fish posing motionless
followed by a color change,
if the shrimp didn't notice it right away
and begin the cleaning.
Cleaner shrimp are a really interesting aquarium inhabitant
and they will actually happily go about their services
when you're working in your tank, picking away at your hand
as you work on whatever it is you're doing.
They're actually often available
as captive bred specimens as well.
And I'd encourage you to try one in your tank
if you have the space.
They do pretty well in all
but the absolute smallest of reef tanks,
but they do only live about two or three years.
I hope you enjoyed the video.
And if you have any cleaner shrimp in your tank,
take a moment to examine their behavior.
Are they signaling at you?
Maybe signaling at your other fish?
It's really interesting to just know a little bit
of their language now.
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Let me know what you thought in the comments down below.
Stay safe, have a fantastic day. Bye.