National Geographic: Rhythms of Life Page #2

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the play of daylight on the reef.

For the fish, stripe and hue holds

clues and communications,

helping them to identify mates,

predators, and prey

in the busy rainbow of the reef.

Trailing twilight in its wake,

a manta ray flies in,

to harvest plankton when again

they rise with evening.

Sunlight fades, taking with it

the world of color,

and the day shift streams off the

reef for the safety of deeper water.

And once again,

the great earth wheels round.

The line between light and darkness

divides those that live by land

as well as the creatures of the sea.

And even the land and sea themselves

breathe with the rhythms

of day and night.

Given off by day,

water vapor now rises, cools,

and condenses in the night air.

From earth, through plants,

into the air,

and back to the earth again

the endless cycles of replenishment

and renewal.

The plants of this Australian

rain forest

have been in tune with the rhythms

of the sun for eons.

Here, an acacia tree wakes up

and stretches for the dawn.

Like a sundial in the trees,

the play of light and shadow

across the forest floor marks

the turning of the planet.

A shifting pool of light holds

treasure for plants and animals alike.

Sunbathers under the leafy canopy,

many plants collect much of their

energy during brief interludes of light.

A boastful bird takes this spotlight

for a stage.

In the dark, his finery is invisible,

meaningless.

Only by day can the male riflebird

capitalize on his gaudy attire.

His appearance, like a feathered,

black-and-white rose,

has been calculated by evolution to

entice females to his side.

A vibrant, sunlit display,

all about sex,

as crisp as the snapping of a fan.

The last hours before sunset often

inspire a flurry of movement.

Once the sun fails,

most birds will lose their powers

of sight and of flight.

They gorge in preparation

for the fast to come.

Color and flair are an advertisement

for plants too.

Their brightly hued fruit

attracts birds,

and with the feast the cycle of life

and rebirth will continue.

For after eating,

the birds will spread the seeds

of new plants far and wide.

While most creatures of the air

depend on the bright of day,

others like fruit bats, are tuned to

more nocturnal rhythms.

All day they had been invisible,

sleeping in the shadows,

saving their energy against

the hot sun.

Now twilight signals to them,

a silent summons.

The bats scramble and take control of

the air the birds have left behind.

Millions crowd the sky,

ever graceful, never colliding.

Foraging in darkness,

the bats have turned to senses

other than sight to find their way.

They navigate the night by sound,

until they find a likely spot

for a meal.

By moonlight,

plants need a different lure

to attract visitors' perfume.

Little is more savory to these bats

than the scent of

ripe blossoms and fruit.

And once they take their fill,

like birds,

they carry seeds everywhere they fly,

assuring the future of

their favorite foods.

The rising moon offers

a gentle promise,

cooling relief from the heat

of the day.

And many creatures bide their time

until the evening hours.

Other mammals have also learned

to maneuver through the midnight air,

like Australia's sugar gliders.

With their built-in parachute,

a sugar glider can span the length

of a football field.

It may seem a bold leap of faith,

but they're only following

family footsteps.

By smearing their scent

upon the branches,

they blaze invisible trails

for their kin to follow.

Their search for insects, sap,

and nectars

carries the gliders into the night.

Like bats, they survey the dark

with sensitive noses.

This evening harvest keeps

these squirrel-like creatures

safe from the predators of day.

Instinct warns them to be back

in their nests by dawn,

before sharp-eyed hawks and eagles

take to the skies.

For millions of years,

mammals were the masters of the night.

In prehistoric days dominated by

dinosaurs, smaller, warm-blooded animals

took advantage of the relative safety

of the darker hours.

But the days when mammals were forced

to hide from the coning of the light

are long since over.

Now, in rain forests round the world,

near the top of the evolutionary ladder,

you'll find agile tree-toppers ready

and willing to celebrate their place

in the sun.

These proud primates,

central American howler monkeys,

inaugurate each day

with a morning chorus,

staking their claim to the trees

and life at the top.

Higher still cling their smaller

cousins, the spider monkeys.

With few natural enemies

they rule the roost.

Grasping hands and feet give them

confidence to live life out on a limb.

And evolution has given them

a whole new point of view

stereoscopic vision.

It gives them the ability to judge

distance precisely an.

And invaluable skill

when hurtling through the treetops

Somewhere deep

in the prehistoric past,

the human line diverged from

that of monkeys and apes.

And even if we no longer get to

work vine to vine,

we still share common genes

and heritage,

and an attachment to

the daytime hours.

It's programming imprinted on us both

by the ever circling sun

and its cold celestial partner.

Lunar rhythms cast long shadows

over daily life on earth.

Though the mile-high tides of creation

have shrunk to swells of mere feet,

the rise and fall of the oceans

still exerts a powerful force.

From 240,000 miles away,

the moon's pull wields power

enough to carve the coastline

and buoy up the polar ice.

Four times a day,

the sea scours the coast,

always retreating, always returning.

It's a force both destructive

and life-giving.

Many creatures thrive here, on the

shifting boundary between sea and land.

On gentler shorelines,

each time the tide retreats,

it leaves behind a feeding ground

replenished by the sea.

The lull between high tides

sees a race for survival,

a race against the lunar clock.

These scavengers must

feed their fill now.

Sand-bubbler crabs pick food

from the net of the sand,

sorting out trapped particles of

seaweed and other plants.

They leave behind

delicate spheres of sand.

It's a temporary testament

to their labors.

Combing the territory

around their burrow,

they scar the sand with their tracks,

each lone scavenger attending to

its own hunting ground.

Other creatures march boldly forward

with the strength of numbers.

Soldier crabs sweeping the shore

in battalions.

Mostly males,

they work together by the hundreds,

exhausting each plot of land

before moving on.

An army of crabs,

a living tide of hungry hunters.

But no army can defend against

the moon, and they know it.

The crabs' parade grounds

will be deserted

by the time the tide marches back

to claim it.

As water replaces land, those

that can, take to the air.

Here the moon is mistress.

She sets the rhythm of life

at all hours,

low tide is time to eat;

high tide, the time to rest.

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