Truly toxic creatures are crawling in every crevice,
every corner of the planet.
The ocean floor, the desert, your closet.
But it's not about you.
They just want to stay alive.
Venom seeps out of their fangs
or poison surges through their flesh.
And, sometimes, a creature wields both weapons.
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Their beauty's undeniable.
Their diversity, striking.
They have both male and female reproductive organs.
And the rare ability to breathe through their skin.
They're armed with tiny, toxic grenades.
And eat poison, to become poison themselves.
A terrifying alien invader?
The freakish result of an experiment gone horribly wrong?
Neither.
They're nudibranchs, also known as sea slugs,
albeit far more stunning than the term slug suggests.
There are over 3000 known varieties
that range from the poles to the tropics.
Nudibranchs thrive in diverse ecosystems.
Their name is as strange as the reason they have it.
Nudibranch means naked gill.
Unlike fish, their gills are on the outside of their body,
feathery and flowing.
They breathe through these external plumes.
These colorful creatures are often finger-sized,
although some can be more than a foot long.
They can drift and twirl in a flamboyant display.
They have a head, but it's not always easy to find.
Their two simple eyes are only capable
of detecting light and dark.
You'd think predators would easily snap up
these tiny creatures, but nudibranchs have many ways
to defend themselves.
Turns out, they don't really need eyes.
Instead they have rhinophores.
These antennae-like structures
are key to a nudibranch's survival.
They sense predators by chemoreception,
which means they can smell danger.
But if and when danger appears,
their flashy colors and patterns are nature's way
of warning would-be hunters that they're a toxic tidbit.
Some species are able to transform the poisons
that they ingest, and re-use it as a defense
by releasing it through their skin.
Other nudibranchs can defend themselves with their cerata,
translucent, horn-like growths that extend
from the nudibranchs' body.
Inside each one of the appendages is sticky thread
and poison-filled barbs.
When predators like fish and crustaceans close in,
these defense mechanisms kick in.
Water rushes into the tentacle, pressure builds,
until the barbed thread shoots outward;
so fast it can pierce a crab's shell.
Not necessarily lethal,
but it can be enough to make predators think twice.
But the hunted is also the hunter,
and these showy sea slugs are voracious eaters.
They will attack jellyfish, and even other types of sea slugs,
but their all time favorite food is coral.
Sensitive to amino acids released by living coral,
they move in once they catch the scent.
These little jewels are survivors, and an unusual
mating ritual helps these exquisite creatures thrive.
They're equipped with both male and female sex organs.
When two nudibranchs connect,
they cross-fertilize each other and both will bear offspring.
And they do it often.
With just 40 days between generations,
it means they can be prolific.
That doesn't mean they're easy to locate.
To most of us, nudibranchs are as extraordinarily alien
as any organism could be.
Cold and calculating.
Skilled and stealthy.
Specialized Killers.
We know them as assassins.
The insect world is full of these cold-hearted killers,
where survival is the name of the game.
In fact, if you're a predatory insect,
you were born to be an assassin.
But one bug family in particular
has earned the name assassin.
This extensive family includes 7,000 species.
So what sets these killers apart
in the brutal insect world
where murderous mayhem fills every minute of every day?
They kill with lightning speed.
And they're equipped with deadly venom.
When assassin bugs go for the kill, they almost never fail.
Some assassin bug species actively hunt.
Others lie in wait, and ambush unsuspecting prey.
Long, front legs pull the victim close with freakish strength.
A dagger-like proboscis penetrates the exoskeleton.
A potent and highly complex venom
is injected directly into the victim.
Within seconds, cell membranes are destroyed,
and paralysis, not death, ends the struggle.
Then, the venom liquefies the insides of the prey,
so that the Assassin bug can suck up the nourishing liquid.
Males and females can find their prey
in the forests, scrublands and grasslands in warmer climates
on almost any continent.
But they're too worldly to settle
for those out of the way places.
If given the chance,
assassin bugs will happily move into a house.
There are lots of places to hide,
and plenty of other insects to feed on in a human home.
During the day they keep a low profile,
but in the dead of night, they emerge from their
tiny catacombs and begin the hunt for a meal.
Not another insect, not a pet.
A human at its most vulnerable: asleep.
Human blood straight from the source.
These assassin bugs are not the first or the last insect
to lay claim to human flesh.
Some assassin bugs, the conenose bugs,
are known for biting humans on the lips.
Like their cousin, the bedbug, these species
are attracted to the carbon dioxide humans exhale.
A ghoulish practice,
and the reason these assassins are known as kissing bugs.
But a venomous kiss can bring with it
something far more insidious.
In the Americas, it can bring Chagas, a parasitic disease.
The symptoms are usually mild, and often undetectable,
but other times Chagas can cause grave damage to major organs,
and could lead to death.
An unnerving thought.
Seems like we'd be better off without them.
Strangely enough, it's not that simple.
Our relationship with these notorious bugs is complicated.
Just like the cold-blooded killers they're named after,
these bugs can be commissioned to do our bidding.
They're excellent predators, and their ferocious hunting prowess
is of great benefit to farmers.
They exterminate thousands of pests,
protecting precious crops in the process.
Most species are rarely more than an inch long,
but with their speed and potent venomous attack,
they can kill insects several times their size.
Like earwigs, caterpillars and beetles.
Like them or not, our entanglement with these
compact killers isn't going away any time soon.
As the global temperature warms, they're moving into new regions,
and they're bringing all of their dangers and benefits
with them.
So good night, sleep tight, and don't let the kissing bugs bite!
Deep below the surface of warm tropical seas,
an unlikely killer,
as beautiful as a richly colored nudibranch,
makes its way across the ocean floor.
This is the flamboyant cuttlefish.
In the large family Sepiidae,
that's filled with strange members, it stands out:
for its brilliant iridescent color,
for its preference to walk rather than swim,
and for the lethal poison it can deliver.
But all cuttlefish have one thing in common:
they're considered some of the greatest hunters on earth.
With some 120 species, they traverse the sea-bottom
and coral reefs in equal measure.
But don't be fooled by their gentle, fluid grace.
Cuttlefish are ruthless,
with a hoard of weapons in their arsenal.
These big-brained creatures are highly evolved,
and extremely intelligent.
Being super smart is a big advantage
in this marine world of cut-throats.
Cuttlefish learn fast, adapting to new environments
in a heart-beat, to quickly scope out the food supply
and the best way to get it.
Their extraordinary eyesight is a weapon unlike any other.
Two giant eyes, very large in relation to their bodies,
are sophisticated marvels.
Even though cuttlefish are color blind, they can spot
details that humans can't even comprehend.
Cuttlefish can see in low light but, more impressively,
their eyes can see polarized light,
allowing them to detect even the slightest motion.
All of this serves to better seek out their prey.
Once its victim is located, the cuttlefish moves in,
slow and stealthy.
What happens next shows just how impressive a predator it is.
A pair of sucker-covered feeding-tentacles moves out
of the cuttle mantle lightning fast,
stunning the target,
then sucking the victim violently back
into its gaping mouth
For shrimp and crab caught in the crosshairs,
the nightmare has just begun.
Waiting in this cuttlefish's mouth is a bone-saw;
a parrot-like beak
that literally rips its victims apart.
However, for large prey like fish,
cuttlefish deploy another option:
toxic saliva that paralyzes their victims
long enough for them to be eaten alive.
Oh, and if you think the cuttlefishes' toxic tendencies
only works on marine creatures, think again.
Besides having a toxic bite, some species of cuttlefish
have poisonous flesh that can be deadly if consumed.
If ingested by humans, the smallest trace can induce
respiratory failure, cardiac arrest and sometimes death.
But you've got to see them to avoid them.
And that's no easy task.
Cuttlefish are shape-shifting masters of disguise,
capable of camouflaging themselves to avoid detection.
When their eyes pick up subtle changes in their environment,
it instantly triggers this color-changing mechanism.
Covering its body are millions of tiny cells
called chromatophores.
These cells develop at birth, giving a cutlet the power
to blend into its surroundings from the beginning.
Like pixels on a computer screen, these electrified cells
allow cuttlefish to change color
and disappear into their environment.
Concealed from view, the camo-wearing killer
lies in wait, the victim hopelessly outmatched.
In a final bizarre twist, the cuttlefish
can also radically change its physical appearance.
By contracting muscles on its skin it can fool
victims and predators alike into thinking it's kelp or coral.
Despite its formidable arsenal,
the cuttlefish does have enemies.
Its meat is a tasty treat for sharks, seals and dolphins.
And in those rare moments when the hunter is hunted,
the cuttlefish knows when to cut and run.
It can flee with enormous speed, leaving only an inky trace.
Meet the giant red-headed centipede.
Actually, you probably don't want to.
It's one of the nastiest invertebrates
in the American southwest.
And it's got legs to die for.
That's terrible news for this unsuspecting cricket.
In a battle for survival, the cricket doesn't stand a chance.
The giant red-headed centipede is actually only 7 inches long,
but it has an enormous presence.
It's got a very tough shell and 42 sharp and sticky legs,
but most importantly,
it has venom that delivers a knock-out punch.
As the cricket is about to discover.
Oblivious, it lingers.
And the centipede waits and watches.
Or it appears to be watching.
Although the centipede has 8 eye clusters on its head
with 200 little eyes each,
the centipede can only detect light and dark.
Another sensory organ proves to be more useful: chemoreceptors,
conveniently located in the centipede's antennae,
detect the chemical traces emitted by its prey.
All the better to smell you with, my dear.
When the right moment comes, the centipede pounces.
And with those appendages, resistance is futile.
The centipede's legs are a straitjacket
from which no insect can escape.
And it uses as many legs as it needs.
Once the cricket is secured, it's time for the coup de grace:
potent venom.
And it's there, at the ready.
The centipede's first pair of legs
are actually venom-filled fangs.
The poison is rich in neurotoxins.
Its prey is immediately paralyzed.
The centipede's powerful jaws easily break through
the cricket's shell.
Wasting no time, it goes straight for the abdomen.
Cracking it open, the centipede gets a pleasant surprise:
eggs - unborn crickets.
Yum!
The centipede uses its palps like chopsticks
to feast on the protein-rich eggs.
It's an easy meal.
With the weapons it possesses,
most meals come easily to the giant centipede.
Even bigger and stronger prey.
Because of its venom, it can paralyze and consume
much larger animals such as lizards, rodents and frogs.
So the leggy creature has no problem being aggressive
when it's hungry.
Once the centipede bites, a combination of intense pain
and paralysis immobilizes its prey.
Despite its ferocity, the giant red-headed centipede
doesn't always prevail.
It can become prey too.
Birds, mammals, and even other centipedes will try their luck.
Their bright colors are meant to be a clear signal
to predators to stay away.
The smart ones do.
But for those that don't,
the giant centipede has yet another trick.
Its tail looks like its head.
The would-be predator has a tough choice.
Bite the wrong end,
and the predator itself risks being bitten.
And death is almost certain.
It makes for a deadly dinnertime gamble.
Alas, humans aren't immune to centipede venom either.
Although most bites only cause sharp pain and swelling,
for those allergic to its venom, a bite can be fatal.
There's a little-known story of a confederate soldier.
A giant red-headed centipede walked over his chest
while he was sleeping, its legs piercing the soldier's flesh.
Swelling, intense pain and convulsions followed,
and the soldier died just two days later.
With the ability to disable and kill much larger animals,
the giant red-headed centipede
is a confident and accomplished predator.
If you see one, beware!
It's one of the most venomous invertebrates in the world.
Venom and poison -
some of nature's deadliest chemical weapons.
Some victims face a gruesome end.
For others, it's a nasty blow.
But it's not personal.
These toxic brutes will do whatever it takes
to find a meal and to survive.
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