Worlds of David Darling > Children's
Encyclopedia of Science > Could You Ever Speak Chimpanzee? > 4. Songsters
of the Sea
COULD YOU EVER SPEAK CHIMPANZEE?
a book in the Could You Ever? series by David Darling
4. Songsters of the Sea
More than two-thirds of the planet's surface is covered by ocean, most of
it unexplored. This is the home of cetaceans, a remarkable group of animals
that includes whales, dolphins, and porpoises.
|A humpback whale breaches,
or leaps above, the ocean's surface
Cetaceans swim and feed in the water like fish. They have the same sleek
shapes and fins as fish. But, like humans, they are warm-blooded, air-breathing
mammals. The females do not lay eggs, but give birth to live babies which
they feed with milk.
Among the cetaceans are the largest animals ever to have lived on Earth.
Biggest of all is the blue whale, a creature so huge that it may weigh as
much as elephants and be as long as three school buses, In a day, a blue
whale can eat 9,000 pounds of food, and in a single swallow it can gulp
down 100 pounds!
One of the most surprising features of cetaceans, though, is the size of
their brains. At 20 pounds, the brain of the sperm whale is the heaviest
of any animal – six times the weight of the heaviest human brain.
Even the familiar bottlenose dolphin, often seen performing at places such
as Sea World, has a slightly bigger brain than that of an adult man or woman.
Though some whales have very large brains, this does not mean they are smarter
than human beings. As with apes, brain size alone is not an accurate guide
to intelligence. What matters more is brain size in relation to body size.
Measured in this way, whales are less intelligent than humans because they
weigh hundreds of times as much. Much of their brain, according to some
scientists, is needed to control their huge bodies.
|Dolphins have twice as many folds as people
do in the front part of the brain
Yet, it may not be as simple as that. When scientists examined the brains
of whales in detail, they found that the brains are especially well developed
in those areas normally devoted to higher thought. Whales have unusually
Researchers know that in humans, the front part of the brain is important
in the ability to make decisions, to solve problems, and to think about
the future of the past. Scientists also believe that the amount of folding
on the front part of the brain is related to intelligence. Human brains,
for instance, are more folded than chimpanzee brains. These, in turn, are
more folded than rabbit brains.
The front part of many whale brains is very large, very folded, and contains
a much greater number of brain cells than a human brain does. It seems unlikely
that this region of a whale's brain would have anything to do with controlling
the animal's great body. Instead, it is probably used for advanced thinking,
just as it is in humans. Still, we do not know for sure.
Whales are difficult to study because they live so differently than humans.
They live in the water, while we live on land. Since whales have fins rather
than hands, they cannot make or use tools. We have hands with which we can
build homes and machines and change the world around us. Whales leave no
trace of their activities on their surroundings. To learn more about whale
intelligence, we must look at the way they behave and, more importantly,
at the way they communicate.
The Mysterious Giants
Millions of people have watched the playful antics and amazing acrobatics
of cetaceans in captivity. Dolphins and killer whales are famous for the
tricks they perform. Yet, that ability alone does not prove that these creatures
are especially intelligent. Properly trained, dogs, horses, and even parrots
will perform crowd-pleasing stunts on command.
|A killer whale performs at
Sea World in San Diego, California
To discover how claver cetaceans really are, they must be studied in the
ocean in their natural habitat. After all, human beings may seem much less
creative if imprisoned than if they are free to do as they like.
To humans, much of whale behavior remains a mystery. But at least some of
the things that whales have been observed doing in the wild suggests they
are remarkable good thinkers.
Perhaps the most fascinating evidence that whales may be highly intelligent
comes from the sounds they make to each other under the sea. Strange, puzzling,
and very complicated, these sounds may be part of a language that we are
still far from being able to understand.
The Songs of the Humpback Whale
In the mid-1960s, three scientists from Princeton University, Roger and
Katherine Payne and Scott McVay, began a study of the weird moans and cries
of humpback whales. First, they listened to tapes that had been made a few
years earlier using a hydrophone – an underwater microphone –
in the seas around Bermuda. Then, they began making their own hydrophone
recordings from a small sailboat. What they discovered was totally unexpected.
Each year, during the winter months, humpback whales gather in the same
part of the ocean to breed. And each year, at this time, the males make
their most beautiful sounds, or "songs." At the beginning of each breeding
season, all the humpbacks arrive singing the same song. As the season progresses,
though, the song gradually changes. By the end of the season, it can hardly
be recognized from what it was at the start. All the whales in a given breeding
area continue to sing the same song, and all keep up to date with the current
version of the song.
During the summer months, when the humpbacks live alone, they do very little
singing. But when the breeding season stars again, they gather once more
and sing the same song that they ended with the year before. Then the whole
cycle is repeated.
Songs from different groups of humpbacks in different parts of the world
show little resemblance to one another. The basic rules, however, seem to
be followed for changing them. Some scientists believe that whales are born
knowing the rules for composing songs. The whales change the songs according
to these rules, and memorize any changes made by nearby singers.
Many animals sing – birds, insects, frogs, bats, and gibbons, to name
just a few. But only humpbacks, as far as we know, change their songs from
year to year. Why they do this is a complete mystery. The whales may enjoy
singing, and their songs may be a way of binding the herd together. Or these
huge sea mammals may actually share thoughts and experiences they have had
during the year, much as human travelers in olden times shared tales by
Based on the evidence known, few scientists would claim that humpbacks are
exchanging complex messages. Yet, the ever-changing songs of the humpback
remain a mystery.
|The Sound World of the Whale
Though whales can see well, that is not much use in detecting objects
over long distances under water, even if the water is clear. It is
no use at all below depths of 1,200 feet, where the ocean is pitch
black. Fortunately, all whales seem to have the ability to find their
way in the water and sight their food through echolocation.
|Using echolocation, a dolphin identifies a
triangle held by a diver (above); a killer whale locates a school
of fish a mile away in two seconds (below).
Not much is known about how whales and dolphins make or hear sounds.
It seems clear that their clicking noises come from air spaces inside
the head. Air may be forced back and forth very quickly in these spaces
to create the clicks. The sounds then move forward through an oil-filled
gap in the creature's forehead. Ther they are focused into a more
powerful beam, just as a magnifying glass can focus the Sun's rays.
When a whale's click strikes a school of fish, it bounces back. What
happens next is not certain. The whale may pick up the returning sound
with its jawbone. Finally, the sound travels down an oil-filled channel
in the jawbone to the inner ear. From the time it takes the click
to travel out and back again, the whale can judge how far away the
Experiments with dolphins have shown that their ability to use echolocation
is highly developed. For example, a blind-folded dolphin can distinguish
triangular shapes from circular ones, or a large circle from a small
one. Even more amazingly, a dolphin can tell by echolocation alone
whether a square object is made of wood, metal, or plastic –
from a distance of 100 feet!
Challenges for the Future
Whales other than humpbacks also fill the ocean with their amazing and beautiful
sounds. The blue whale makes what is probably the loudest sound of any animal.
These enormous creatures can make themselves heard above the background
noise of the ocean for tens or even hundreds of miles. Yet that may not
be very far compared to the distances whale calls may one have traveled.
|The fluke of a humpback whale. In the future,
scientists may learn more about the mysterious songs of these giants
of the sea.
Very large cetaceans, such as the blue whale and its close relative the
fin whale, produce sounds that cover an extremely wide range. Some of these
sounds are too low for human ears to hear, and others are too high. Today,
because of the constant throb of ships' propellers, the ocean is a comparatively
noisy place. But until 170 years ago, it was much quieter. Centuries ago,
whales were able to each other's cries over a far greater distance. According
to some scientists, the deepest moans of creatures such as the blue and
the fin whale may have carried through seawater for thousands of miles.
If this is true, then any two whales could have heard each other's calls,
even if they were on opposite sides of the ocean.
There are many unsolved mysteries surrounding the whales. Perhaps, in years
to come, scientists will be able to decode the whales' language so that
we can understand what they are communicating to one another. Or we may
find that cetaceans think in such a different way from humans that we shall
never unlock the secrets of their songs.
In recent years, scientists have made much progress in communicating with
apes. But this has not been achieved by learning the details of how apes
send messages to ne another. The apes' own language seems to fall well short
of what these creatures are actually capable of expressing. Instead, the
real breakthrough in ape-human communication has come by teaching chimpanzees
and gorillas to use a version of our own language.
At the Kewalo Basin Marine Mammal Laboratory at the University of Hawaii,
Dr. Louis Herman has carried out similar experiments with dolphins. Herman
and his staff taught two dolphins, named Phoenix and Akekamai, to respond
to about 40 different whistle sounds, These sounds stand for words such
as fetch, ball, and frisbee. The dolphins understand
short sentences made from these words. What is more, they see, to understand
the importance of the order of words in a sentence – an ability that
not even apes possess. As research in this field advances, some exciting
years may lie ahead in our efforts to share thoughts with other species
of life on Earth.