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Basking in sunlight
a sperm whale rests after its journey
from the black depths of the ocean
Sperm whales are the deepest diving of all mammals
and can spend up to ninety minutes on the sea floor hunting giant squid
and other bottom dwellers
Like mammals on land
all whales and their dolphin cousins are warm-blooded
and need to breathe air
So, how have whales adapted terrestrial organs
to a life at sea so successfully?
And what prompted their ancestors to move
from the land to the oceans?
WHALES
The blue whale is the largest animal
ever to have inhabited the planet
Growing up to one hundred feet
and weighing as much as one hundred and ninety tons
or three hundred eighty thousand pounds
lt is also extremely rare
Only its need to breathe
allows us a fleeting glimpse of its legendary bulk
The blue whale belongs to the order Cetacea
which includes the great whales
and their much smaller relations
porpoises and dolphins
The smallest of dolphins is a fraction
of the size of a blue whale's fluke
At a little over four feet
Hector's dolphins are also rare
Their range is limited to a few coastal areas of New Zealand
where they hunt for fish near the surface
As mammals
whales use lungs to breathe air rather than gills to breathe water
Whale's lungs are relatively small
but they are remarkably efficient
When a whale surfaces
it can replace up to ninety percent of the air
in its lungs in just a few seconds
But this efficiency alone cannot account
for its ability to stay underwater
in some species, for as long as two hours
A diving whale descends
with almost half its total oxygen stored in the muscles
where it is slowly released overtime
The whale uses this oxygen with great economy
Only essential organs, such as the brain
are supplied while others go into oxygen debt
until the animal returns to the surface
But the deep diving sperm whale needs more than these adaptations
lts bulbous head contains the so called spermaceti organ
Filled with a complex mixture of fats and waxes
one of the organ's functions is almost certainly to act
as a biological ballast tank
When water is drawn into the huge nasal passages
the mixture cools and hardens helping the whale to descend rapidly
The process is reversed by ejecting the water and pumping warm blood
through the organ to liquefy the wax
All whales have bones that are light and filled
with oil which acts as an aid to buoyancy
lt's also a vital energy reserve during periods of fasting
Whales are powerful swimmers with tail flukes
that are horizontal rather than vertical, as in fish
The flukes are boneless and consists of strong, fibrous tissue
Powered by a pair of massive muscle blocks forward of the flukes
whales cruise at six miles an hour
with the fastest reported speed in excess of forty miles an hour
Unlike cold-blooded fish
whales need to stay warm in frigid waters
Blubber, a layer of fat up to twenty inches thick
acts as thermal insulation
But whales can also actively conserve heat
using warm blood pumped from the heart
Areas with little or no blubber
such as the head and flukes
operate a heat exchange system
Cooled blood in the extremities is partly heated as it passes
by the warmer blood
A vital adaptation because heat from a body immersed in water
is lost around twenty-five times faster than in air
The very cold waters, thousands of feet below the surface
are the natural hunting grounds of the sperm whale
Sperm whales are the largest of the toothed whales
part of the group that includes the orca or killer whale
With up to ten or twelve pairs of cone-shaped teeth
orcas can threaten even the largest prey
And it's the only whale that can kill other whales
Dolphins also belong to the toothed whale group
and feed on fast moving fish and squid
Dolphins have even moved into some large rivers
where they have become highly specialized
Primitive river dolphins like the Amazon Buto have limited eyesight
and use echolocation to find their prey in murky waters
Echolocation or sonar
has only been used by humans since World War l l. .
. . . but evolved in toothed whales and dolphins over millions of years
Dolphins emit short pulses of ultrasonic sound
that bounce off objects producing echoes
which the animal uses to create sound pictures of its surroundings
Among the constantly shifting ice floes
and channels of the Arctic seas
the ability to navigate beyond the limits of vision is vital to survival
Another toothed whale, the beluga. .
. . . has extraordinary sensory skills
including a highly tuned sonar navigation system
Complex muscles above the jaw focus a beam of sound
that produces a very precise image of its surroundings
enabling the whale to plot a safe route
through channels under the ice
The belugas may descend to a thousand feet to
echolocate scarce breathing holes in the ice
Their acute hearing also helps them evade predatory polar bears
The largest whales and therefore the largest animals
on Earth don't have teeth at all
and feed on the world's smallest animals
These zooplankton in turn feed on minute sea plants called phytoplankton
Floating crustaceans known as krill are among the larger zooplankton
During the summer months
their swarms form concentrations dense enough
to discolor surface waters for many square miles
These super swarms have been estimated
to weigh over two million tons
A blue whale feeding on krill
may take in one hundred thirty pounds in one mouthful
and up to four tons a day in the richest Antarctic seas
ln a unique adaptation
some whales evolved baleen plates as a simple replacement to teeth
enabling them to harvest these swarms
Rows of these plates are suspended
from ridges in the upper jaw
Baleen whales feed by simply opening their mouths
to take in both prey and water
By closing their mouths and raising up the tongue
the water is expelled through the baleen plates filtering out the food
Baleen itself is made of keratin like hair and fingernails
> From hundreds of plates hang countless hairlike fibers
that can filter the vast quantities of food
Gray whales, the most primitive of the toothless whales
evolved thick, bristly baleen to
rake the seabed dislodging crustaceans embedded in the sand
Many whales spend most of their lives feeding
but the oceans do not contain endless supplies
Off the coast of Baja, California
blue and fin whales hunt for food
ln the summer months
the waters near the coast are especially plentiful
and so they and other whales congregate in large numbers
to cruise among the dense shoals of fish
The whales' activities incite a feeding frenzy
among pelicans and other sea birds
Fin whales feed by lunging moving rapidly sideways
through shoals of prey with mouths open
Expandable throat pleats increase the volume of water
and therefore the amount of food taken in
in a single lunge
Fin whales grow to over seventy feet
on a relatively small range of foods that include krill
squid and some small fish
Pelicans capitalize on the havoc wrought by the feeding fin whales
Large whales also require enormous amounts of food
because they need to build up reserves
for the less productive winter season
Humpbacks cooperate to harvest the sea
using a skillfully woven fishing net to encircle their prey
Swimming well below the surface
they weave a net by forcing bubbles out through their blowholes
by moving in a spiral beneath a shoal of fish
The bubbles drive the fish towards the center of the net
Surging towards the surface in unison
the humpbacks form an inescapable phalanx of gaping mouths
Orcas or killer whales cooperate in a different way
Orcas can be aggressive intelligent predators
Here they deliberately beach themselves to capture young sea lions
Shoreline feeding has been passed down through the generations
Adults showing their young how to achieve the best results
This technique echoes the moment in evolutionary time
when the land bound ancestors of all whales first became sea mammals
At that time fifty-five million years ago
the drifting continents were changing the face of the Earth
lndia moved north to collide with Asia
forming the massive heights of the Himalayas from
what was the floor of the ancient Tethay Sea
The remaining water which today forms the Mediterranean
became shallow and more saline
fueling an explosion of sea life
On the edges of this remnant sea in a primeval world
of tropical swamps and estuaries
lived a group of animals known as Creodonts
A sub-group of the Creodonts known
as the Mesonychids hunted close to the water
Some ate plants, but others were opportunistic scavengers
carnivores that fed on dead fish washed up by the tide
Eventually these carnivores hunted exclusively along the tide line
entering the surf to capture dead or dying prey
Within a few million years
they had developed into semi-aquatic creatures feeding wholly in the sea
. . .the first primitive whales
ln the last few decades
scientists have gradually uncovered the mystery. .
. . .of how a land mammal returned to the sea
Near Santa Barbara on the Californian coast
new finds like this twelve million year old skull of a whale
are adding to an emerging picture of how whales evolved
At this stage, scientists Louise Kearin
and Lawrence Barnes are not sure exactly
what is inside the rock
But painstaking excavation will eventually
allow them to place this animal
within a complex evolutionary jigsaw
One that is already relatively complete
The whale story begins with the amphibious animal
that evolved from Mesonychids
Pachocetus, the earliest known whale still had four limbs
as it explored its aquatic environment fifty million years ago
> From then on, they evolved rapidly
Ambliocetus had large hind feet clearly adapted for swimming
Then later Rotocetus evolved a feature
that enabled them to venture further from the land
The tail vertebrae detached from each other allowing the tail
to move up and down for propulsion
Ziggarisa lived around forty million years ago
lt had a flexible forelimb
but the hind limb had now almost disappeared
Ziggarisa showed another important adaptation
The blowhole moved toward the top of the head
ln just over ten million years
the early whales had left the land forever
These primitive whales had teeth designed to grasp and shear
but eventually they became modified to
form long rows of sharp uniform teeth
Today's toothed whales, dolphins
orcas, and sperm whale are their descendants
Around twenty-five million years ago
the baleen whales evolved from a toothed ancestor
Even today
the fetuses of some baleen whales have remnants of teeth
For a land mammal to have evolved into the creatures we see today
such as this minke whale
evolution had to be chemical as well as physical
Kidneys became specialized to deal with excess salt
Fluids covered the eyes to protect them from the saline environment
No other mammal has a covering so sleek
These small adjustments taken together
transformed medium-sized land mammals
into huge sea creatures
At just under one hundred feet long
a Boeing 7 37 is shorter than the largest recorded blue whale
A blue whale's heart is the size of a Volkswagen
And the whale itself is six times heavier than the plane
Their immense size meant that the great whales
were able to fuel a hemisphere
Whale oil lit the continents for many centuries
and later lubricated the machines of the lndustrial Age
European and American whalers made huge profits
unaware they were hunting their quarry to the edge of extinction
Whales were not only killed for their blubber
The strong and flexible baleen from their mouths
was used in a range of domestic products
from corsets to umbrellas
Decade after decade tens of thousands of whales
were slaughtered to satisfy the needs of a burgeoning human population
Herman Melville's story of Moby Dick
the mythic great white sperm whale
told of high adventure, obsession
and an existence fraught with danger
By the mid-1 9th Century
whaling methods had changed little
from earlier days of subsistence hunting
lt was still an intimate struggle between men and whales
A disaster was always looming
By the turn of the 20th Century
even the biggest whales were pursued in the polar regions
and processed in vast factories. .
. . .yielding handsome profits to the new whaling magnates
Most highly prized was the fine oily wax
from the head of the sperm whale
to be used to oil precision machinery
But as catching methods changed
so did the use of the whales
Whale oil no longer lubricated the world
and carcasses were rendered down for soap
margarine, fertilizers, cosmetics
and to provide food for pets and farm animals
''Thank you, Ladies and Gentlemen
and welcome to Shamu Stadium.''
Human attitudes have changed significantly
since mass whaling ended
And whales now hold a special place in our collective conscience
''Come on, folks
Now who wants to see some magic?''
We've come to recognize
that whales are highly intelligent capable of sophisticated interaction
with other species like ourselves and able to imitate and learn
Whales are even adaptable
and successful in some pretty unusual situations
Whales and dolphins are essentially social animals
For some, like these dolphins
belonging to a large group. .
. . . has clear benefits for survival
The chances of finding food are increased
since the group can range far wider than one individual
Collective defense against predators is more likely to succeed
and grouping helps bring individuals together for breeding
Dolphins can congregate in the hundreds
Their schools are fluid
with individuals leaving to join other groups
but with a corps of members that stays together
The much larger whales rarely school
and the closest bond is probably
between a solitary mother and calf
Baleen whales come together at feeding grounds and to mate
but then disperse rapidly
However, sperm whales
the largest of the toothed whales
do group together in pods in warmer waters
Females form the corps of the pod
which also consists of calves
and juveniles of both sexes
Sperm whale bulls spend most of the year alone
hunting in colder waters
But during the breeding season
they join the pod forming a harem
ln this rarely filmed display of strange and sensual behavior
all the sperm whales in the pod
form a knot of writhing bodies
lts purpose is unclear
but it may be a means of reinforcing social bonds within the pod
lt may also have a more directly sexual function
since this encounter seemed to stimulate the immature males
Pilot whales also live in tightly knit groups
but they are often led by a single older female
Strong social bonds like these may hold a clue to
one of the most perplexing mysteries about whales
their apparently deliberate strandings on shore
Evidence from stranding sites suggest
that some animals had parasitic infestations of the ear
and brain to such a degree
that it may have caused disorientation
An infected dominant female could easily lead her entire group
into dangerously shallow waters
But not all scientists agree
that these infestations are the only answer
Others point to magnetite particles found
in the brain of several species
that may be acting as an internal compass
These particles may detect the Earth's magnetic field
which originates deep within the planet
and draws an unseen grid across the globe
lf whales are using this geo-magnetic information to navigate
it's possible that this system breaks
down leading them into shallow water traps
Some whales look like floating reefs
They're a place in the vastness of the sea for parasites to call home
Whales are host to many kinds of parasites
Barnacles that attach themselves to the skin do little harm
but other creatures feed on the whale's flesh
Whale lice have claws that can cling onto a rapidly moving animal
and jaws designed to pierce its flesh
The lice may cause only minor irritation
but the whale's attempts to dislodge them can be spectacular
Spring arrives in the Arctic and as the ice recedes
it's a time for renewal
Beluga whales move en masse
from the ocean to the newly reopened river inlets
All whales shed skin and parasites during their lives
but belugas are the only whales
that migrate to certain areas in the Arctic
specifically to molt their skin
They wait for the tide to enter the fresh water shallows
where a gravel and sand river bed will help them remove old skin
During the year
a coat of yellow-green algae builds up
on the upper body and this, too, will be shed
Small lead groups of beluga enter the river mouth
even though they are vulnerable to polar bears in such shallow waters
As the tide peaks, hundreds of whales begin rubbing
and scratching against the river bed and each other
After a few days
they will return to their feeding grounds in the open sea
scarred in some places
but parasite free and with sleek white skin
With the evolution of sociability among whales
came the development of highly sophisticated communication
Whales vocalize almost continuously
and produce a range of sounds
that is remarkably diverse
Underwater, sound travels four times faster and much further. .
. . .than it does in air
All whales need to emit sounds over large distances for identification
and to locate other whales in the wilderness of the sea
ln this way, whales constantly send
and receive information about sex and activity
Sperm whales use a series of clicks known as codas
lt appears that one whale will call
and another will answer with exactly the same coda
This will be repeated on different occasions
by different individuals in the group
ln other areas of the oceans, populations of sperm whales
have different codas indicating the existence of dialects
within the sperm whale language
One of the more remarkable features of whale communication
is the plaintive alluring song of a lone humpback whale
ln an attempt to attract a mate
a male may sing for more than twenty-four hours
with only a few short breaks to breathe
His song may last up to thirty-five minutes before being repeated
A whale's song is quite clearly defined
with a recognizable beginning middle and end
lndividual songs have their own peculiarities
their own syllables phrases and themes
Sound is one way of attracting a mate
However for a female narwhal living in icy Arctic waters
sight takes precedence in the search for a suitable partner
Male narwhals which grow to about fifteen feet have ivory tusks
that are up to ten feet long
Males joust with these elongated swords
which are both weapons and symbols of dominance
The successful competitor wins the right to mate with females
The strongest male passing on its genes to future generations
Among southern right whales
male competition is intense
The idea is not to be the first to mate, but the last
Because southern right males have the largest testes on Earth
each weighing close to half a ton
the last male to mate not only deposits huge quantities of sperm
but washes out that of the preceding males
This gives his sperm the best chance to reach the female's egg
Many whales migrate huge distances to mate
But the master mariner is the gray whale
lts journey is the longest of any mammal. .
. . .an eleven thousand mile round trip
From October whales begin migrating south
from the Bering Sea in Gulf of Alaska
hugging the North American coastline
down to the warm water lagoons of Baja California
The annual migrations of gray whales are synchronized
with their mating patterns
Conception and birth always occur in these Baja waters
because gestation periods last twelve months
Calving every two years
places enormous biological strain on those females
that conceive regularly
But the warm waters of tropical breeding grounds
may help sustain both females
and their newborns
Twelve feet long and eighteen hundred pounds at birth
a young humpback grows rapidly over several months nourished
by a rich milk that contains up to fifty percent fat and protein
Before it weans
the young humpback may increase its weight by five times
feeding on a hundred fifty gallons of milk each day
Apart from the occasional snack
a mother will not feed while nursing its young
even though a huge amount of energy is used up to produce
such a large offspring
A mother must also protect its young from threats
that can come from any direction
To a pack of hungry killer whales
any newborn whale is a tempting target
Of course the greatest threat to all whales comes
from another species of mammal altogether
Humans began whaling during the first migrations
from Siberia to the Americas
These early settlers survived in a hostile environment
by making full use of dead or stranded
whales as a rich source of food oil and shelter
Recognizing the whale's value
they soon developed hunting techniques to keep themselves supplied
for the long winter months
Today, subsistence whaling is still part of life in the frozen North
This narwhal will provide good eating for the weeks ahead
The skin and blubber will be cut and dried
providing food that is rich in Vitamin C
ln earlier days the slower species that came close to the shore
such as the bowhead and right whales were hunted in open boats
using hand-crafted spears
Most of the animal would have been used including dried bones
used to construct frames for shelters
The annual catch of whale populations was small
and life in the Arctic remained relatively stable
for many centuries until the coming of a new threat
the commercial whalers
But today the mass slaughter of the great whales is all but over
Conservation groups fought long
and hard to close the whaling stations
but by the time mass whaling had ended
over three-quarters of the world's population of great whales
had been obliterated
Communities that once depended on the whaling trade
are now sustained by a new industry
Whale Watching Eco-Tourism
Even though many of the whales are protected as endangered species
it may be a century or more before the most heavily hunted can recover
One positive step came in 1 994 with the creation of a Southern sanctuary
in the seas surrounding Antarctica
a haven for eighty percent of the world's remaining great whales
During the fifty million year odyssey
myriad sea mammals evolved from a terrestrial creature
that hunted the shores of ancient oceans
They gradually lost those features
that associated them with the land
now spawning their young into the oceans
where they would spend their entire lives
Adaptations to new food sources created a mammal without teeth
the baleen whale
New ways evolved to navigate the immensity of the sea
to dive to the bottom of the ocean
and overcome the dangers of the deep
They became social animals that now hunt together
play together and call out across the ocean vastness
THE END
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