every spring the male alligators put on
a spectacular mating display they sink
down in the water so their backs are
just below the surface and make really
low-frequency sounds and the consequence
of that is that water droplets on their
back look like they're dancing and it
soon becomes a water dance-off as rival
males compete by displaying two females
I've never really had any desire to be
close to a bellowing alligator but I do
want to see this and to do it I've got
to trigger a chorus of amorous
alligators
to see the spectacle hella needs to
encourage some alligators to start
dancing and to do this she needs to
replicate their infrasonic calls so they
think there's a larger male close by and
that requires speakers even bigger than
a campervan these speakers produce
sounds of 19 Hertz the same deep
frequency as the alligators bellow at so
let's see if they can entice a grumpy
alligator to start flirting
so that's it those are the big
infrasound speakers sending sound out
over the lake here and now we just have
to wait and see if any of the alligators
react
I'm going straight with that tail up in
the air getting ready to call there are
two parts to this display
deep bellow from their mouths slight
hearing dinosaurs
and the water dance
although we can't hear it these
alligators are actually producing a very
low-frequency hum
and this causes water droplets to bounce
off their bags
for these ancient predators this
elaborate display is essential for
attracting mates
but how do they make the water dance
just using sound
footage from our high-speed camera
reveals their secret
the alligators bag is just below the
surface of the water as it begins to
bellow its entire body vibrates and its
back acts like a piston driving the
surface of the water into a dramatic
splashing display
it's thought that alligators have been
calling like this for at least 70
million years
you