The dance of the dung beetle Marcus Byrne
this is food and what I want to do today
is share my passion for poo with you
which might be quite difficult but I
think what you might find more
fascinating is the way these small
animals deal with poo so this animal
here has got a brain about the size of a
grain of rice and yet it can do things
that you and I couldn’t possibly
entertain the idea of doing and
basically it’s all evolved to handle its
food source which is dumb so the
question is where do we start this story
and it seems appropriate to start at the
end because this is a waste product that
comes out of other animals but it still
contains nutrients and there are
sufficient nutrients in there for dung
beetles basically to make a living and
so dumb beetles eat dung and their
larvae are also dumb feeders they are
grown completely in a ball of dung
within South Africa we’ve got about 800
species of dung beetles in Africa we’ve
got 2,000 species of dung beetles and in
the world we have about 6,000 species of
dung beetles so according to dung
beetles dhoni is pretty good but unless
you’re prepared to get dung under your
fingernails and route through the dung
itself you’ll never see ninety percent
of the dung beetle species because they
go directly into the dump straight down
below it and then they shuttle back and
forth between the done at the soil
surface and a nest they make underground
so the question is is how do they deal
with this material and most dung beetles
actually wrap it into a package of some
sort ten percent of the species actually
make a ball and this fall they roll away
from the dong sauce usually bury it at a
remote place away from the dung source
and they have a very particular behavior
by which they are able to roll their
balls so this is a very proud owner
at the beautiful dung ball you can see
it some mail because he’s got a little
hair on the back of his leg there and
he’s clearly very pleased about what
he’s sitting on there and then he’s
about to become a victim of a vicious
smash-and-grab and this is a clear
indication that this is a valuable
resource and so valuable resources have
to be looked after and guarded in a
particular way and we think the reason
they roll the balls away is because of
this because of the competition that is
involved in getting hold of that done so
this dump at was actually well it wasn’t
done about 15 minutes before this
photograph was taken and we think it’s
the intense competition that makes the
beetles so well adapted to rolling balls
of dung so what do you better imagine
here is this animal here moving across
the African felt its head is down it’s
walking backwards it’s the most bizarre
way to actually transport your food in
any particular direction and at the same
time it’s got to deal with the heat this
is Africa it’s hot so what I want to
share with you now are some of the
experiments that myself my colleagues
have used to investigate our dung
beetles deal with these problems so
watch this people and there’s two things
that I would like you to be aware of the
first is how it deals with this obstacle
that we’ve put in its way see there’s a
little dance and then it carries on in
exactly the same direction that it took
in the first place Neil Vance and then
heads off in a particular direction so
clearly this animal knows where it’s
going and it knows where it wants to go
and that’s a very very important thing
because if you think about it you’re at
the dung pile you’ve got this great big
pies that you want to get away from
everybody else and the quickest way to
do it is in a straight line so we gave
them some more tests to deal with and
what we did here is we turned the world
under there
feet from what response so this animal
has actually had the whole world turn
under its feet it’s turned by 90 degrees
but it doesn’t flinch it knows exactly
where it wants to go and it heads off in
that particular direction so our next
question then was highly doing this what
are they doing there was a culet that
was available to us was it every now and
then they climb on top of the ball and
they take a look at the world around
them and what do you think they could be
looking at is a climb on top of the ball
what are the obvious cues that this
animal could use to direct its movement
and the most obvious one is to look at
the sky and so we thought now what could
they be looking at in the sky and the
obvious thing to look at is the Sun so a
classic experiment here in that what we
did is removes the Sun what we’re going
to do now is shade the Sun of the board
and then move the Sun with a mirror to a
completely different position and look
at what the beetle does does a little
double dance and then it heads back in
exactly the same direction twins in the
first place what happens then so clearly
they’re looking at Sun Sun is a very
important human scarf for them the thing
is the Sun is not always available to
you because at sunset disappears below
the horizon what was happening in the
sky here is that there’s a great big
pattern of polarized light in the sky
that you and I can’t seize the way our
eyes are built but the Sun is that their
horizon over here and we know that when
Sun is at the horizon sets over on this
side there is a north-south a huge pass
way across the sky of polarized light
that we can’t see but the Beatles
conceived so how do we test that well
that’s easy what we do is we get a great
big polarization filter pop the beetle
Indonesia
and the filter is at right angles to the
polarization packages sky beeping comes
out from underneath the filter and it
does right hand to him because it comes
back under the sky that it was
originally it orientated too and then re
already takes itself back to the
direction it was originally going so
obviously Beatles can see polarized
light okay so what we’ve got so far is
what a Beatles doing they’re rolling
balls how they doing it well they
rolling in them in a straight line how
they maintaining it in a stroke
particular straight line well they’re
looking at celestial cues in the sky
some of which you and I can’t see but
how do they pick up those celestial cues
that was what the interest to us next
and it was this particular little
behaviors our dance that we thought was
important because look it takes her paws
every now and then and then heads off in
the direction that it wants to go in so
what are they doing when they do this
dense have far can we push them before
they will reorient eight themselves and
in this experiment here what we did was
we force them into a channel and you can
see he wasn’t particularly forced into
this particular channel and we gradually
displaced the beetle by 180 degrees
until this individual ends up going
exactly the opposite direction that it
wanted to go in in the first place and
let’s see what his reaction is because
he’s headed through 90 degrees here and
now he’s going to when you end up down
here is going to be a hundred and eighty
degrees in the wrong direction and see
what his responses does a little dance
turns around and heads beckons he knows
exactly where he’s going he knows
exactly what the problem is and he knows
exactly how to deal with it and the day
is this transition behavior that allows
them to reorient eight themselves so
that’s the dense but have to spending
many years sitting in the African bush
watching dung beetles on nice hot days
we notice that there was another
behavior associated with the dance
behavior every hand then when they climb
on top of the ball they wipe their face
and you see him do it again now he’s not
know what could be going on here the
clearly the ground is very hot too when
the ground is hot they danced more often
and when they do this particular dance
they wiped the bottom of their face and
we thought that it could be a
thermoregulatory behavior we could we
thought that maybe what they’re doing is
trying to get off the hot soil and also
spitting on to their face to cool their
head down so what we did was design a
couple of arenas one was hot one was
cold we shaded this one we left that one
hot and then what we did was we filmed
them with a thermal camera so what
you’re looking at here is heat image of
the system and what you can see here
emerging from the poo is a cool dung
ball so the truth is if you look at the
temperature over here don’t is cool
so all we’re interested in here is
comparing the temperature of the beetle
against the background so the background
here is around about 50 degrees
centigrade the beetle itself on the ball
are probably around about 30 to 35
degrees centigrade so this is a great
big ball of ice cream that this beetle
is now transporting across the hot felt
it isn’t climbing it isn’t dancing
because its body temperature is actually
relatively loads about the same as yours
and mine and what’s of interest here is
that little brain is quite cool but if
we contrast now what happens in a hot
environment look at the temperature of
the soil it’s up around 55 to 60 degrees
centigrade watch how often the beetle
dances and look at its front legs their
roaring Lee hot so the ball leaves a
little thermal shadow and the beetle
climbs on top of the ball and wipes its
face and all the time it’s trying to
cool itself down we think and avoid the
hot sand that it’s walking across and
what we did then was put little boots on
these legs because this was a way to
test it’s a legs were involved in
sensing the temperature of the soil and
if you look over here with boots they
climb onto the balls far less often when
they had no boots on so we described
these as cool boots it was a dental
compound that we used to make these
boots and we also pull down the dung
ball so we were able to put the ball in
the fridge gave them an icicle dung ball
and they climbed onto that ball far less
often then when they had a hot ball so
this is called still ting it’s a thermal
behavior that you and I do if we cross
the beach we jump onto a hop onto a
towel somebody else’s towel sorry I
jumped onto your tail and then you
scuttle across on somebody else’s to
hell and you in that way you don’t burn
your feet and that’s exactly what the
beetles are doing here however there’s
one more story I’d like to share with
you and that’s this particular species
it it’s from a genius called soma
there are sir
species in the genus and they have a
particular behavior that I think you
will find interesting this is a dung
beetle watch what he’s doing Tran you
spot the difference they don’t normally
go this slowly it’s a slow motion but
it’s walking forwards and it’s actually
taking a pellet of dry done with it this
is a different species in the same genus
but exactly the same foraging behavior
there’s one more interesting aspect of
this dung beetles behavior that we found
quite fascinating and that’s that it
forages and provisions are nest so watch
this individual here and what he’s
trying to do is set up a nest and using
like his first position but he comes up
with a second position and about 50
minutes later that nest is finished and
he heads off to forage and provision at
a pile of dried dung pellets and what I
want you to notice is that outward path
compared to the homewood path and
compare the two and by and large you’ll
see that the homewood passes far more
direct than that outward path on the
outlet pass he’s always on the lookout
for a new blob of dumb on the way how he
knows where home is and he wants to go
straight to it the important thing here
is that this is not a one-way trip as in
most done beetles the trip here is
repeated back and forth between a
provisioning site and a nest site and
watch you’re going to see another South
African crime taking place right now
his neighbor steals one of his dumb
Phillips so what we’re looking at here
is a behavior called pass integration
and what’s taking place is that the
beetle it’s got a home spot it goes out
on a convoluted path looking for food
and then when it finds food it heads
straight home it knows exactly where it
turn these now there’s two ways it could
be doing that and we can test that by
displacing the beetle to a new position
when it’s at the foraging site if it’s
using landmarks it will find its home if
it is using something called path
integration it will not find its home it
will arrive at the wrong spot and what
it’s doing here that’s using pass
integration is its counting its steps or
measuring the distance out in this
direction it knows the bearing home and
it knows it should be in that direction
if you displace it it ends up in the
wrong place so let’s see what happens
when we put this beetle to the test with
a similar experiment so here’s our
cunning experimental he displaces the
beetle and now we have to see what is
going to take place what we’ve got is a
burrow that’s where the forage was the
foragers been displaced to a new
position if he’s using landmark
orientation he should be able to find
the Burrow because they’ll be able to
recognize the landmarks around it if
he’s using a path integration then it
should end up in the wrong spot over
here so let’s watch what happens when we
put the people through the whole test so
there is there he’s about to head home
and look what happens
shame it hasn’t a clue it starts to
search for its house in the right
distance away from the food but it’s
clearly completely lost so we know now
that this animal uses pet integration to
find its way around and the callous
experimental leaves at top legs so what
we’re looking at here are a group of
animals that use a compass and they use
the Sun as a compass to find their way
around and they have some sort of system
for measuring that distance and we know
that these species here actually can’t
the stitch that’s what they used as an
odometer a step counting system to find
their way back home we don’t know yet
what dung beetles use so what have we
learned from these animals with a brain
that’s the size of a grain of rice well
we know that they can roll balls in a
straight line using celestial cues we
know that the dance behavior is an
orientation behavior it’s also
thermoregulation behavior and we also
know that they use a pat integration
system for finding their way home so for
a small animal dealing with a fairly
revolting substance we can actually
learn an awful lot from these things
doing behaviors that you and I couldn’t
possibly do thank you