A kilometer from the surface
beyond the reach of the sun,
a giant black void larger
than all the rest of the world's
habitats combined.
There's life here,
but not as we know it.
Alien like creatures
produce dazzling displays of light.
Nearly all animals need to attract
mates and repel predators.
This language of light
is so widespread here that these signals
are probably the commonest form
of communication
on the entire planet,
and yet we still know
little about them.
Hunters illuminate themselves,
and by doing so, attract inquisitive
prey.
This is Fang Tooth,
It has the largest teeth
for its size of any fish.
There are precious sensors
all over its head and body
which can detect anything
moving in the surrounding water.
It's the midnight zone's
most voracious fish,
but prey use light
as a distraction,
a decoy of luminous ink.
Down here
in this blackness,
creatures live beyond
the normal rules of time.
Siphonophores are virtually eternal.
They repeatedly clone themselves,
some eventually going longer
than a blue whale.
Down here, it snows.
Continuous clouds of organic debris
drift slowly down from above.
This is food
and a whole variety of filter feeders
depend on it.
Jellyfish
and delicate
sea cucumbers.
The 1% of marine
snow they miss
eventually settles on the sea floor.
Over millions of years,
it forms a layer of mud up to a kilometer
thick.
It's an empty plane that covers
half the surface of our planet.
The deep seabed
may at first appear lifeless,
but it's home
to a unique cast of mud dwellers.
The sea toad.
It is an ambush
predator with an enormous mouth
and infinite patience.
This fish
has been living for so long here
that its fins have changed
into something more useful,
feet.
They help in shuffling
about on the sea floor.
The Flapback Octopus.
it hovers just above the surface of the mud
as it delicately sifts
through it, searching for worms.
But it can jet away
at the first sign of danger.