National Geographic: Ocean Drifters Page #2

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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.

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