[MUSIC PLAYING]
NARRATOR: This giant aquatic scorpion, almost three feet
long, was one of the first predators
ever to emerge on planet Earth.
The primeval oceans teemed with many different species
of scorpion-like creatures.
The largest sea scorpions, or eurypterids,
reached more than 7 feet long, 1,000
times the weight of the largest scorpion alive today.
And research indicates that eurypterids liked
to devour members of their own species,
taking down prey weighing maybe 180 pounds.
What puzzles some researchers is how
sea scorpions were able to crunch
through their well-armored prey.
A modern-day scorpion may provide the answer.
Paleobiologist David Marshall is going
to analyze the components of a modern-day scorpion's weapons.
DAVE MARSHALL: Well, we managed to get a scorpion exoskeleton.
And we took the teeth from that, and we
put it in the microscope.
You can see here that we've got the teeth of the scorpion,
and all of the teeth are white, which means that they're
made out of a heavier element.
So we've got a spectrum here which
shows all the different elements,
and if we look at the teeth, what
you can see is that there's a little spike of zinc here.
NARRATOR: It turns out that the claws have metal in them.
This concentration of zinc in the claws
is a natural process which evolved
over time to make modern scorpions
more efficient predators.
But he's enlisted the help of a blacksmith
to investigate just how those metal-tip claws may
have worked.
At his forge in the heart of the English countryside,
the blacksmith will make two steel sword blades.
Both will be identical to the naked eye,
but one will be given a specially-hardened cutting
edge, just like the scorpion's claw.
It's a process known as case hardening, where
the outer surface is coated with a compound that increases
the carbon content, and therefore the hardness
of the steel blade.
Adding carbon to metal increases its strength,
and so, too, does adding metal to the cuticle of arthropods.
Changes their material properties.
We're putting the hard skin on to what
would be a soft piece of metal.
But on the case-hardened area, it just glides straight off.
It's absolutely solid.
First we've got our mild steel blade.
We'll see how it performs against a piece of oak,
and see if the blade sustains any damage.
Straightaway, you can see we've lost the edge.
We've significantly dulled the edge.
Prolonged use of the blade against this piece of wood
would severely damage the edge.
Now we'll see how the case-hardened blade compares.
NARRATOR: The sword is as sharp as ever because
of that hardened outer skin.
But how well can it slice through flesh,
like a hungry sea scorpion had to do?
DAVE MARSHALL: Now we've made our hardened blade.
All we've got to do is really test it.
I'm going to do that on this piece of meat.
NARRATOR: Once the sea scorpion had penetrated the outer shell
of its prey, it would have made short work of the flesh inside.
And so these aquatic monsters, possibly armed
with metal-reinforced claws like today's modern scorpions,
were the world's first large predator.