From a distance, they look like shadows on the water.
The ones we're approaching lie just along the California coast.
There's a forest under here, and these are the tops of its trees.
This is a forest of giant kelp:
The largest plants in the ocean...
...as tall as office buildings.
On the surface, trees this tall would need rigid trunks.
Not the giant kelp.
Tiny floats along each stem are enough to hold it up.
It is anchored to the ocean floor by a root-like structure called a holdfast.
No nourishment is provided through the holdfast.
All nutrients are absorbed directly from the water itself.
Every habitat on earth has evolved its own village of relationships...
...its own citizens.
All sharks sink unless they swim.
This female swell shark has settled here for a purpose.
Every few months she lays a single egg.
Ten months later, helped by little hooks on its back...
...the baby swell shark will struggle from its case.
This is the approach to life his species has evolved:
They begin it alone.
This fiery little sentry is a garibaldi.
The nest he's guarding is that dark patch on the side of the rock.
Moray eels have powerful, crushing jaws and sharp teeth...
...but they are not a threat to the garibaldi. The prey they lie in wait for is octopus.
The octopus has blundered into the Garibaldiˇ¦s nest.
Morays stalk their victims not by sight, but smell.
That squirt of ink contains an anesthetic that foils the moray's sensitive nose.
Like a banner on a castle wall, the dazzling garibaldi posts himself...
...on his ramparts, a guard whose watch is never done.
He protects his nest from hungry fish and scavengers.
Sea urchins are a constant annoyance.
It's the male garibaldi who makes the nest...
...nibbling it neatly out of a patch of algae.
He ends up with a space about a foot and a half across.
This nest already has eggs in it, but if the male keeps things tidy...
...he may still attract another female.
When he sees her, he goes straight to the courtship acrobatics.
Each time he does a loop, he clucks twice.
The courtship worked.
The female is laying eggs.
From time to time the male moves in to fertilize the eggs.
Since the female will eat the eggs if she gets the chance...
...her fierce little partner chases her away as soon as the laying is done.
In a couple of weeks a swarm of tiny garibaldi will drift away on the current...
...to join the ebb and flow of other new life in the underwater forest.
Many will be caught and consumed by animals like this tube anemone...
...a creature that snares its food in a thicket of stinging tentacles.
Others will escape to a great living mass of minute plants and animals...
...called ocean plankton.
But even there they are still food.
The pelagic jellyfish harvests them with a paralyzing sting.
The face of an escarpment below the kelp forest.
These corals look like plants, but they're animals.
Their branches comb the passing current for plankton.
Deeper, lies an even stranger world:
A vast shag carpet of diminutive starfish known as brittle stars.
A sheep crab gallops clumsily across the brittle star garden.
Is this kelp crab about to make a meal of his captive?
No. The larger crab is a male.
He shelters and protects the female who is carrying a brood of eggs.
These sarcastic fringe heads...
...yes, they are called sarcastic fringe heads...
...have moved into adjacent empty shells.
The trouble is they're both males.
In the face of threats like these, one will have to leave...
...and his vacant shell will be available for a female.
Night gathers.
A hungry sun star storms through a mass of brittle stars, who flee in panic.
When daylight fades...
...creatures who shun the light of day emerge from their lairs.
Darkness is their special cloak.
The California spiny lobster is protected by a tough hide...
...as hard as a rock, called an exoskeleton.
The only trouble with this suit of armor is that it has to be thrown away...
...once a year, for the lobster to grow.
It's called molting.
The lobster has already leaked out enzymes.
The enzymes weaken his old shell.
Now he drinks large amounts of water in order to put pressure on the shell.
Next, he expels the water from his body, allowing him to struggle out of his shell.
It's an exhausting process.
For 10 minutes the lobster is defenseless.
The new shell will be soft and pliable.
Before it hardens the lobster will drink...
...steadily swelling his body...
...until he's about a quarter of an inch bigger than he was last year.
As the night deepens...
...strangers ascend from the depths.
Tonight, and only tonight...
...the opalescent squid will mate.
In a frenzy they seize each other, coupling again and again.
When a male succeeds, his tentacles flush red.
Females produce egg cases almost as long as their bodies.
With strong threads, they anchor the cases in the sand...
...covering the ocean floor with swaying drifts of progeny.
And this is how it ends...
...every adult will die.
In the world of the kelp forest, nothing goes to waste...
...and every death provides a meal to life.
Bat rays awaken to the feast.
Sea lions are stuffed to the whiskers with squid.
What are these sea lions doing?
Your guess is as good as ours. No one's ever witnessed this before.
Every morning they arrive to chew these stems.
We don't know why.
Maybe this is the way sea lions brush their teeth.
This rocky environment was once a part of the kelp forest.
It's been transformed into its present state by sea urchins.
It's called an urchin barrens.
Sea urchins have a powerful appetite for kelp.
Here they are stripping the ocean bare.
Whole forests are set adrift by these spiny little regiments.
Packed as densely as 300 per square yard...
...the urchins devour the giant kelp's holdfasts.
But the urchins have enemies, too...
...and the sun star is a deadly one.
There's a balance here.
The urchins eat the kelp, the sunstar eats the urchins...
...the giant kelp returns.
The endless flux of ruin and renewal...
...of life itself.
Like fish made of light...
...a school of Spanish mackerel hunts along the edge of the forest.
Special organs in their sides help them weave and dart in harmony...
...as if they were a single creature.
We are drawn to the ocean.
Life came from the sea, and perhaps all life longs to return to it.
Each species follows its separate thread...
...but a thread that knits its fate into the fate of others.
None is exempt from this...
...on land or in the sea.
The destiny of each is tied to all