The human mind
has always had a fascination
with worlds beyond our own
Following the stars across the seas,
early explorers
imagined that they might meet
weird creatures in undiscovered lands.
They never guessed
that under their keels,
drifting in the same currents
that carried their ships,
were life forms far stranger
than anything they could imagine.
It's a world where the forces
of pressure and darkness
have given rise to creatures
as different as on another planet.
Their whole existence is shaped
by the great ocean currents,
which sweep them endlessly
around the biggest living space
in the solar system.
At the edge of this alien world,
here in Florida,
one ocean drifter comes
from the beach itself.
It can take these hatchlings three days
to claw their way up
from nests buried two feet deep.
They may look like land animals now,
but sea turtles have evolved
for 80 million years
to be riders of the ocean currents.
These loggerhead turtles,
no larger than a child's hand,
are about to embark on a perilous
As they head down the beach,
they're already reading
the earth's magnetic field
with their internal compass.
Only one hatchling in a thousand
will survive to adulthood
and ride the currents back to
this beach to breed.
It's among the most extraordinary
odysseys in nature.
This is the story of one loggerhead's
journey into the unknown world
of the ocean drifters.
Like a windup toy, the hatchling swims
relentlessly out into the ocean.
The waves tell her which way to go
away from shore and from
predators stalking the shallow water.
Danger causes her to tuck in her limbs
disguising herself as floating debris.
The shark doesn't see her and swims on
As she heads toward the safety
of deep water,
the hatchling joins a rich tide
of other marine creatures.
Every rock and weed is home to
a different species.
Coastal waters are the fertile
breeding ground for the oceans.
Florida may produce five million
loggerhead hatchlings each year.
In some coastal species,
from a single female.
The eggs of this sea urchin
and the smoky clouds of sperm
from a nearby male
swirl together in a fertility dance
on the ocean floor.
Huge quantities of eggs and
larvae produced along the coastline
will be drawn into the ocean currents.
Most will become food
for other marine creatures.
Setting their offspring adrift
might not sound like good
parental care.
But it's a valuable survival mechanism
for many coastal species.
It lets them populate new areas
and encourages the exchange
of genetic material.
All through the night, instinct
drives the loggerhead to push on.
The outpouring of new life
on the continental shelf below her
is just as persistent.
With the bellows like action
of her pleopods,
the spiny lobster sends
It's a reproductive blizzard.
The lobster's larvae have evolved
a flattened shape;
it suits them for the drifting life
as ideally as a snowflake.
After 36 hours of swimming,
the hatchling is growing tired.
In the clear water 30 miles off
the Florida Coast,
she reaches the edge
of the Gulf Stream,
and finds shelter in the drift lines
of sargassum weed.
This plant spends its
whole life floating on the open sea,
held up by small air bladders.
The sargassum provides a haven
in a vast, featureless world.
All kinds of creatures
find harbor here.
For the first time in her life,
the loggerhead can rest.
But the stillness is an illusion.
The winds have piled up the sargassum
weed in drift lines
along the edge of one of the most
powerful currents in the world.
Just beyond,
the Gulf Stream hurtles by.
Viewed from space, the Earth is alive
with clouds caught up in the rhythm
of the tradewinds.
These winds
and the rotation of the planet
generate the great ocean currents.
The loggerhead will be traveling
for years
in a circle of currents called
the North Atlantic gyre.
Her journey starts off Florida
in the warm waters of the Gulf Stream,
which will carry her
north past Cape Cod.
Satellite imagery is teaching us
that the Gulf Stream
is a wild living carousel,
spinning off side currents,
and stirring up a broth of marine life
The edges of currents are the
great way stations of the open sea.
Plant and animal drifters are drawn
into these fronts,
one species making life possible
for another.
For a hungry animal,
it's an oasis in an oceanic desert.
The sargassum becomes a perch
for goose barnacles.
They glean food particles
from the plankton,
the rich soup of plants and animals,
many of them microscopic.
Even sluggish homebodies
can be marvelously adapted for travel
in the larval stage.
The glorious creature drifting
on wing-like lobes is a snail.
Some snail larvae use tentacle
like arms
for feeding and to keep from sinking.
Some may by able to remain
in this stage from months
until they drift to a suitable habitat
Everything is kept lightweight
for easier travel.
Look closely and you can see
the spiral of a transparent shell.
These beautiful drifters move
so gracefully,
you forget that the Gulf Stream is
hurrying them along at 100 miles a day
Microscopic larvae spawned in Florida
could eventually settle
on the shores of Africa.
And the next generation
may ride the currents back.
The ocean drifters have little to eat
except each other
which they do eagerly.
So if the sargassum weed
provides shelter,
it also harbors death
in an astounding diversity of forms,
often wonderfully camouflaged.
The sea horse has evolved
a mild and plant-like demeanor.
But it's still a predator
and keenly watchful.
It drops down to ambush
its planktonic prey.
Then loops itself back
into the sargassum
to avoid being ambushed itself.
The entire food chain is caught up
in this dangerous game
of deception and self-defense.
Small fern-like animals known
as hydroids
colonize the sargassum
and feed on the most minute plankton.
A sea slug grazes in turn on hydroids.
The slug's camouflage doesn't fool
a potential predator.
But the sea slug has armed itself
with chemical defenses from its prey.
The file fish abandons the attack.
But another creature's camouflage
will soon bring the fish to a gory end
The drifting weed may look innocuous.
But look again.
A fish hoping to harvest hydroids
from this leafy growth
would find itself staring
into a malignant eye.
Evolution has made
the four-inch long sargassum fish
the big bad wolf
of this floating world.
Its extraordinary camouflage doesn't
just mimic the coloration of the plant
The white spots also mimic
the tube worms
and hydroids that grow on sargassum.
Its pectoral fins have evolved
into prehensile fingers,
the better to creep through
the foliage.
It will eat creatures
almost its own size,
and its victims thrash around
in its gut momentarily before they die
The loggerhead swims directly
under this hidden peril.
But the sargassum fish
lets her pass by.
Hungry dolphin fish
won't be so particular.
These big, fast-moving fish can devour
all life on the weed lines.
The turtle scramble for a hiding place
Now the loggerhead pushes
onto deeper water.
Beyond the sargassum in the open sea,
gelatinous drifters
are the most abundant life form.
They may be the loggerhead's main
source of food for much of her journey
A jellyfish like this
may be more than 95 percent water.
But the thin membrane of
living tissue is still nutritious.
We know almost nothing
about how the turtle
or any other animal survives here.
We act as if this is our planet
and we call it Earth.
But the oceans are so large
and so deep that they constitute
more than 99 percent
of the inhabitable world.
Even for oceanographers,
the open sea is an alien environment,
tantalizing and yet largely unexplored
Each creature in the currents
has its own story to tell,
its own extraordinary adaptations
to life on the open sea.
Humans venturing into these waters
with scuba gear
study only the upper layers
of the ocean.
They stay tethered to a rope,
like astronauts walking in space.
It's a 500 mile swim to shore.
Richard Harbison
and his colleague Larry Madin
are among the few researchers studying
how these ocean drifters behave
in their own environment.
The air tanks limit them
to 25 minutes per dive.
So they get just a glimpse of how
these high sea drifters really live.
Harbison and Madin specialize
in creatures of incredible delicacy
known as jelly plankton.
This underwater world changes
by the hour.
Many species stay away
from the brightly lit surface by day,
so these researchers dive round
the clock.
Under the cover of darkness,
a whole new world of creatures rises
from the depths.
It is the largest animal migration
on the planet,
and it happens every night
in the oceans.
This sea snail
joins a glorious host of species
as they ascend to feed at the surface.
Life as a jelly
is an ingenious adaptation.
There are no hard surfaces
to run into on the open sea,
so these drifters don't need
a sturdy body.
The gelatinous form gives them the
same buoyancy as the water around them
They've evolved for life at sea by
becoming organized seawater themselves
Near the surface, the smaller drifters
feed on minute plant life
that's been growing all day in the sun.
Bigger animals come up to feed on them
The great oceanic food chain
begins here
and everything else depends on it
This weird apparition is a killing
machine for small crustaceans.
The writhing arms of this comb jelly
startle its victims,
which flee straight into the wing
like feeding lobes
at either end
and become entangled.
It's easy to become mesmerized
by the delicate structures
of some ghostly creature turning
gently in the currents.
You can see the beating of the heart
through the transparent shell.
Its mouth parts
are like an easterlily.
Ocean conditions have reshaped
it beyond all our notions
of what a snail should be.
Look in another direction,
and there's a salp chain grazing
on small plant particles.
This jelly can reproduce
with extraordinary speed
to take immediate advantage
of a new food source.
The salp sprouts new individuals
like a chain of paper dolls.
The gelatinous form makes
for efficient feeding.
It allows this siphonophore
to spin out lengthy tentacles
like fishing lines.
It twitches its crustacean-like lures
to entice its prey.
In the boundless world of mid-ocean,
with the sea bottom miles below
and no other surfaces nearby,
a jelly is the only niche
for other species.
One animal's body can become
the whole world for another.
A crustacean deposits her offspring
on a comb jelly.
As they grow, they devour their host.
Crustacenas eat jellies,
and jellies eat crustaceans.
It's a banquet where it's difficult to
distinguish the guests from the dinner.
The jellies also prey on one another.
The jelly plankton even have
their own great white shark.
The three-inch-long beroe
is a jelly with jawa.
Its mouth is lined with sharp,
tooth-like hooks.
The beroe latches onto its prey
and then expands to engulf it.
This ability to stretch is another
advantage of the gelatinous form.
Though scuba researchers
are limited to working
in the upper layers of the ocean,
with this submersible,
an oceanographer can study
drifting life forms down to 3,000 feet
There the world of the ocean drifters
becomes even more fantastic.
Edith Widder studies creatures living
in the deep sea currents.
Her pilot maneuvers skillfully
as he collects samples
with a battery of scientific equipment
On the way down,
they may be the first humans
to see creatures that have
drifted here for millions of years
endlessly strange and wonderful.
A siphonophore spirals out into
the watery darkness, like a galaxy.
It's maximizing the feeding area
for its fringe of stinging tentacles.
Scientists have only
recently discovered
this football-size comb jelly.
They call it Big Red.
This fish isn't sick.
In these dark unbounded depths,
with no top and no bottom,
everything simply behaves differently.
Like this squid suspended
in the stillness.
Or this squid which has developed
a transparent gelatinous body.
All the rules are different down here.
Researchers freely admit that what they
know about almost any of these animals
is less than a paragraph.
Scientists have given
this newly discovered deep-sea octopus
the nickname Oumbo.
Wider specializes in bioluminescence,
the ability of living creatures
to communicate by producing light.
To study this phenomenon,
she measures what happens
when bioluminescent animals drift
into this screen.
She must shut down her own floodlights
and use special cameras
to see how they respond.
The pitch blackness of deep water
suddenly explodes in a fiery light show
A sea cucumber
looks strange enough just before
it makes contact with the screen.
Then it turns on its own lights,
and rolls off unharmed.
Almost every animal
uses bioluminescence
in the pitch dark of the deep.
Given the abundance
of life in the oceans,
This may be the most common
form of communication on earth.
The clouds of bioluminescence
can be so bright
that they light up the instruments
inside the submersible
If attacked
some animals try to confuse their
predator with sheer incandescence,
like a flashbulb in the face.
Others illuminate the predator
in the hope that some larger predator
will come along like a cop
and take it away.
Some use light like a lure
to draw their prey close,
or to attract a mate.
In this world of darkness,
the language of light is so important
that a moment's flickering
may determine whether
an animal lives or dies.
But what we know about bioluminescence
is limited by the difficulties
of ocean research.
Even a submersible stays underwater
for only about three hours.
The promise of oceanography
is tantalizing.
Bioluminescent chemicals
are already being used in medicine.
But reaping the potential benefits
is dangerous work.
In many ways, it's like the grand
adventure of space travel.
But we've mapped the barren surface
of Venus in far more detail
than our own deep ocean floor.
Is it worth exploring the depths
of this planet?
In one area the size
of a small living room,
deep sea researchers recently
discovered 460 new species.
Who knows what secrets
we have yet to discover in the oceans?
Even back on the surface,
the limits of our knowledge can be
painfully apparent.
In the complex ecosystem
at the very skin of the ocean,
a whole other world of creatures
lives both in and out of the water.
As it moves, the stinging tentacles
of the Portuguese man o' war
stream out to gather food.
By raising its gas-filled sail,
the man o' war can travel
at varying angles to the wind.
It's an elegant system
for dispersing animals
not just where the current takes them,
but across the face of the ocean.
Nothing about the man o' war is simple
It's neither an individual animal,
nor a colony, but something in between
Joined together under the gas bladder
is a kind of cooperative assembly
of stomachs,
tentacles, and reproductive organs.
Other species add to the complexity.
One fish, called nomeus,
hides out among the deadly veil
of tentacles.
The man o' war toxin is
more potent than the cobra's.
But perhaps because
of a protective mucus layer
or greater immune resistance,
nomeus can dine unharmed
on the man o' war itself.
Other fish aren't so lucky.
The man o' war can stretch
its tentacles out more than 50 feet,
and each tentacle is studded
with batteries of stinging cells.
Nomeus may help out the man o' war by
herding these fish toward their death.
Triggered by the fish,
the stinging cells fire slender
threads lines with barbs.
The victim is lassoed, hog-tied,
and injected with paralyzing poison.
Then the digestive organs move in.
Like some monstrous lifeform,
they wriggle and twist
as they fasten their flexible mouths
onto the victim.
Gradually, they engulf the fish
and dissolve its flesh.
After half a year,
the young loggerheads odyssey
has taken her to mid-ocean.
But she still has a lot to learn.
All the activity around
the man o' war catches her eye.
She just wants to grab
a few fishy tidbits
and doesn't seem to notice
the nasty business overhead.
For a moment, the turtle looks like
a puppet on a deadly set of strings.
But it's the man o' war
that's in danger.
The turtle turns her hungry eye
on this intriguing new possibility.
People talk about the first
brave human who ate an oyster.
But what a tangled and spicy meal
the man o' war must make.
The turtle's skin may be too thick
for the stingers to penetrate.
But no one knows what protects
the turtle's eyes and mouth.
The loggerhead soon pushes on
in search of a meal
that's not quite so challenging.
One of the strangest inhabitants
of the harsh world
between air and water is the drifting
nudibranch named glaucus.
This upside-down sea slug swallows air
bubbles to hold itself at the surface.
With its pointy appendages,
it latches onto anything
it's lucky enough to bump into.
But what it's really after are
the deadly tentacles of the man o' war
It coats its mouthparts
with a mucus layer to protect itself.
The smaller less powerful
stinging cells get digested.
But the most virulent stingers
remain intact.
Amazingly, they pass directly
to the nudibranch's extremities
and it uses them for its own defense.
But these surface drifters
must face adversaries even more
formidable than each other.
A storm is brooding up
across the water.
It's a reminder of how unstable life
must be on the very face of the ocean.
One moment these creatures are
being scorched by sun and wind,
and the next they're tumbling
in storm-tossed waves.
As the storm passes,
they get pelted by icy rain
and have to endure the dilution
of their salty home.
Yet the animals living in
the ever-changing surface
can seem so delicate.
This drifting snail
builds a fragile home of air bubbles
sealed in an envelope of mucus
then hangs on for dear life.
If it lets go,
it'll sink into the abyss.
The raft is also holding up
the snail's offspring,
in these egg capsules.
It's a cradle at the top
of a hostile world.
When it's done laying eggs,
the snail builds a new raft for itself
and cuts its 50,000 offspring adrift.
Natural debris also drifts
in the surface currents.
It's always been a means of dispersal
for some plants.
A coconut from the Caribbean
may ride the Atlantic
currents thousands of miles
to take root on some distant shore.
Fish are drawn to this kind
of flotsam for shelter.
A drifting crate can turn
into a small ecosystem,
Where fish lay eggs
or find their food.
But the little things
we throw away add up,
and the supply of garbage begins
to seem endless.
One study estimated that
was being heaved overboard
by ocean-going vessels alone
A recent treaty now regulates
the practice,
but it's rarely enforced.
Whatever goes into the ocean
gets drawn into the currents,
and it builds up in the very places
where marine life is richest.
Animals encrusted on debris may rouse
the loggerhead's hunger and curiosity.
For her, drifting objects have always
been a natural food source.
Until recently, a loggerhead could safely
eat almost anything she came across.
Nothing in her evolution
has prepared her
for this wealth of deadly new choices.
To her, it makes as much sense to pick
at the festive remnants of a balloon
as at a man o' war.
Fragments like these
can choke turtles to death.
Plastic blocks their digestive tracts
and causes starvation.
This time, she's unable to
tear off a bite.
But she'll face many more
opportunities as she swims on.
Almost every dead turtle found
has plastic in its gut.
Millions of seabirds also die
each year because of garbage
like this gannet tangled up in debris
absent-mindedly discarded
by sportfishermen.
Commercial fishermen lose thousands
of miles of net each year,
which spread out all across
the oceans like a deadly web.
There may be no way for the loggerhead
to learn about these new perils
until it's too late.
The turtle has survived her first year
But in the long seasons before she
circles home to Florida to lay her eggs
a more sinister peril may threaten her
Everything out here
is absorbing a swelling tide
of chemical wastes
even the plankton.
Though they may seem insignificant,
the lifeforms here are important
to cloud formation.
They even help regulate
the global climate.
These microscopic plants and animals
have always struggled against
enormous odds to reach maturity
Now they must also absorb heavy metals
sewage, pesticides and petrochemicals.
Plankton is the base of the food chain
and every marine animal depends on it.
If our carelessness disrupts this vast
drifting tide of life,
will it imperil the entire ocean?
Will it affect the food we eat
and the very air we breathe?
No one has yet spent
enough time traveling
in the loggerhead's world to find out.
It may be that we humans
will always find it easier to turn our
imaginations away from the oceans
and out to other worlds
But as we peer up at the stars,
we should keep one truth in mind
All the alien life forms we know
and perhaps all we ever will know
are here adrift on planet Earth.