National Geographic: Ocean Drifters Page #2

---

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

Rate this script:0.0 / 0 votes