Kind: captions
Language: en
finding scorpions in the desert at night
is surprisingly easy all you need is an
UltraViolet torch because scorpions are
incredibly fluorescent fluoresent means
their bodies absorb ultraviolet light
and radiate it in the visible part of
the spectrum they glow this bright neon
green color but scorpions aren't the
only animals that flues jellyfish
amphibians owls and even platypuses glow
under ultraviolet light part of this
video is sponsored by C When shopping
more about them at the end of the
show I'm out here in the desert near
Bakersfield California looking for
scorpions with Carl clook a professor of
biology at Cal State Bakersfield he's
been researching scorpion fluoresence
for over a decade if you have a black
light it's really pretty easy if they're
there you're going to spot them does he
look like he's in a posture to like
defend himself yeah he's not real happy
okay grab my high-tech scorpion catching
equipment here it's a tongue depressor
with a yellow highlighter on it so it
fluoresces in the black light so you can
see where it is got
it best technique is usually to put the
V behind him
mhm that in front of
him that was impressive all right should
we give it a
shot got
one and then just gently pokes him back
in and they usually just kind of do a
little side crab walk back there you go
and just tilt it up oh
unbelievable unbelievable all right I'm
I'm going to get him but why are
scorpions fluorescent I've got about 12
hypotheses so you test them one at a
time um you have 12 hypotheses about why
the Scorpion fles more like six actually
I was being a little bit almost all
scorpions flues I haven't seen it myself
but some that live that live in caves
that don't Flor us but it's only like
one very small group all the other
scorpions for us one possibility is just
that this is a relic trait it's
something they developed way back when
they first came out on land and just
haven't lost a chemical that has another
function that just happens to fluores
there are plenty of chemicals that
fluores I mean we have um internal bily
fluids that fluores and clearly those
are never exposed to UV light so the
idea of having a function for that
fluoresence is kind of silly this
fluores is about the same color is a
scorpion but clearly isn't a scorpion
it's actually a rock the color is a
little off but but that is like what is
it it's plastic from a milk bottle huh
you wanted to know if the Scorpions were
fluorescing in order to attract insects
right so how did you test that what I
did was I used preser scorpions like
these ones and I took half of them and
dipped them in UV blocking marine
varnish so they didn't fluores and then
I just used um basically fly paper and
took those things outside and set them
side by side and then found the number
of flying insects that were were caught
in each so we were outside in Moonlight
um and I did the same experiment both
under the new moon and the full moon and
so what I found from that was when it
was a new moon there was no difference
in the number of insects caught by the
fluorescent nonf florescent scorpions
but under the full moon when there's
nice bright UV light available there was
a difference and the ones that flues
actually caught fewer insects it seems
kind of counterintuitive so that tells
me that my hypothesis was wrong which
happens a lot basically yeah they're not
they're not using their fluoresence to
lure insects in fact the fluoresence is
a bad thing for them in terms of their
ability to catch flying insects at least
but let me ask you this if you find that
fluoresence is counterproductive for the
Scorpion in some way doesn't that
indicate that there has to be something
useful that exactly there must be
something that counteracts that sort of
negative negative yeah scorpions are
really well adapted for what they do one
of the cool things here is that
scorpions um are actually able to
metabolize um iron and nickel and in
their
um pincer here and on the tips of their
claws they actually have basically iron
to uh strengthen that iron and
nickel at the end of their tail yeah
yeah you can see like the color here is
a little bit different and it's because
of the iron in it that seems very
aggressive to
me one of the main things we're
interested in here is how they see so
I've seen two of their eyes so those are
the median eyes right there those two
dark spots yep there's a cluster of
three eyes right right there and of
course on the other side so they're
symmetrical so they have a total of
eight eyes can they detect light with
parts of their body that are not eyes
yeah actually they can in a 1968
experiment researchers put scorpions in
half covered Petri dishes then they
exposed them to Bright Light and all the
Scorpions quickly hid under the covered
part of the petri dish then the
researchers painted over the eyes of the
Scorpions so they couldn't see and
repeated the experiment but when they
turned on the light 93% of the time the
blinded scorpions still scuttled over to
the covered side the finding was
remarkable scorpions don't need their
eyes to detect light they can sense it
with their bodies it show that they have
what's called an extraocular light sense
in their tail so they can detect light
with their tail they can't form images
they can't but they can detect light the
tail of a scorpion can detect light one
hypothesis is that they use it to
communicate with one another
um idea being that they use it to
determine primarily whether or not
another scorpion out there is of the
same species for mating one fairly low
probability hypothesis is that they can
use it as
camouflage because they absorb UV light
um if they're sitting on another surface
that absorbs UV light and you have an
organism that seas in the UV like some
owls and things like that can do um they
would tend to blend in very nicely with
that so it's a possibility but not that
many organisms
CN UV and not that many that uh eat
scorpion C and UV so it doesn't seem
very
likely there he is you go for it you
want me to do it first you do it close
here you go see get him go wow one of
the ideas is scorpions came out of the
water a saluran period long time ago and
there was a lot more UV just in sunlight
and things like that then because we
didn't have an ozone layer we didn't
have you know all these things that are
blocking UV in our at osphere now and so
that one of the ideas is that it
actually acts as a sunscreen and its way
to absorb those um damaging ultraviolet
photons and convert them away into
something and and basically keep them
from penetrating into the body and
causing damage go in your
home there you go we got them and then
there have been some other ones are a
little bit more out there um one of
which being the one that I've actually
settled on at the end is that they use
it as part of their sensory system to
detect the presence of flight in the
environment so this was a later
experiment after I gave up on the
initial idea I show that didn't work so
all I really did in that one very simple
put a scorpion in each one of these
things here and then put this under
ultraviolet light and exposed it to
ultravet light and so I measured how
long they spent exposed versus unexposed
and how many times they went back and
forth and you were testing scorpions
that were fluorescent and not
fluorescent right so what I did with
that was I developed a technique to
remove or at least reduce the ability of
scorpions to Fluor out Simply by
exposing them for long periods of time
to ultraviolet light so basically you're
just kind of taking the chemical that is
causing fluoresence in their exoskeleton
and you're photo bleaching so you're
you're making the chemical not be able
to work function properly anymore what
we found is the activity levels um
changed significantly so when you
exposed in UV light the non-fluorescent
Scorpions acted like they were in the
dark there was no between their behavior
in the dark and and UV light whereas
when UV light was present for the ones
that could fluores they reduced their
activity levels what what's the
conclusion from that uh the conclusion
from that is that the fluoresence itself
is acting as a way to um for them to
detect the presence of ultraviolet
another um researcher guy by the name of
Douglas Gaffin um came up with a great
phrase for it I wish I'd come up with
the phrase but I got to give credit um
he calls it a whole body Photon detector
so it's part of their sensory system
what we don't know is why they want to
detect ultraviolet light so badly that
they've turned their whole body into a
photon detector the suspicion is that it
has to do with determining um whether or
not they should come out at night the
idea is when UV light hits a scorpion's
body it fluoresces and the tail detects
this emitted green light alerting the
Scorpion that it is exposed so it
searches for cover but scorpions are
really good at starving for long periods
of time they don't need to eat that
often mhm and coming out and foraging is
dangerous for them mhm and so they don't
like to come out when it's a Moonlight
night typically the only ones you'll
find out in a full moon are the ones
that are really hungry really need food
if they're well fed they'll stay down so
they're using that as basically their
que of the environment and saying you
know okay this is how bright it is so
that's a cue as to how likely I'm to get
prayed upon and then here's how hungry I
am that's a cue as how badly I need to
get out and get some food and then the
trade-off between those two is basically
should I go out tonight or should I stay
in my hole Yeah
sh