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 10-year journey around the ocean.
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,
500 million offspring may come 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 700,000 hatchlings seaward.
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 easter lily.
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 13 tons of trash per minute
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 perilss
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.