Dolphins Essay, Research Paper
Dolphins
There are many differences between Dolphins and Porpoises. People
might think that the two are the same mammal, but they are not.
Dolphins have cone-shaped teeth and porpoises have spade-shape
teeth. The easiest way to tell them apart is that the porpoise is
smaller in size and is broader across the back. Dolphins are
classified in the Delphinidae species and there are thirty to fifty
different kinds of species in this family(Minasian 204). The
Porpoises are classified under the Phoceonidae family which is
Latin for pig-fish. Dolphins are the smartest mammals in the ocean.
Navy ships have used dolphins to detect mines in the water and
search out enemy submarines. Dolphins are very friendly mammals;
there are places in Florida where one can ride the dolphin in the
water many dream of such a ride.
This dream might not come true if people and different companies
keep on killing them. We need to recognize the value of these
dolphins and the dangers facing them, and get to stop these dangers
and save this amazing creature. The three main dangers and threats
to dolphins are pollutants, tuna boats and people.
Dolphins are very sacred creatures to many people. When two
dolphins are in a symbol with one pointing up and the other one
pointing down it symbolizes ?The duel cosmic streams of involution
and evolution? (McIntyre 31). The symbol is the way of showing how
the dolphin evolved and where it is going. The dolphin by itself
means ?Allegory of Salvation inspired in the ancient legends which
show it as the friend of man?(McIntyre 31). It tells the fable of a
dolphin saving a man.
The ancients believed that the dolphin represented the vital power
of the sea or water which symbolizes the source of life. The Greek
word for dolphin is Delphys which means womb and is known as the
?living womb of the sea of creation?(McIntyre 34). Many of the Gods
were based on the dolphin because they believed it could partake in
mythological forms. There are many stories about dolphins and gods
and how they help the gods from the sea. There are also a lot of
symbols that represent the dolphins in little story blocks. This is
probably why dolphins are a form of good luck or sacred to us in
this century(McIntyre 33).
Dolphins are among a very few mammals and animals with the
intelligence similar to our own. Cetacean (which is what dolphins,
whales and porpoises are classified under)brains are larger than
human brains in memory and conceptual thought. There are three
animal types with comparable mental equipment; these are humans,
elephants and cetaceans. Humans are superior in the physical sense,
but might be lacking in the intelligence phase. According to John
Lilly:
You see, what I have found after twelve years of work with
dolphins is that the limits are not in them, the limits are in
us. So I had to go away and find out, who am I? What?s
this all about?(qtd. McIntyre 57)
What Lilly is saying is basically that the dolphins have no limits,
they can keep going and do anything for a long time, but we limit
ourselves and while we are doing this the dolphins are gaining more
intelligence.
The dolphin uses sonar like in a navy ship to detect dangers and
other things in the waters. Sonar is a device using underwater
sound waves for navigation, range finding, detection of submerged
objects, communications and etc.(Readers Digest Dictionary 1278).
Since their echolocation system gives them detailed images of
objects in the ocean, they might be able to recreate sounds and
project images to one another. According to Peter Warshall:
Both man and cetaceans seem to have a tremendous capacity
for digital information exchange (information understood on
the basis of its sequence in time and space, like written words
or the Morse Code) using variations in pitch and frequency.
Cetaceans may also have analog communications systems
which are so different from our own that we may not
be able to perceive them. (Analog information is information
you understand because the data itself is like what you are
talking about. For example, the word ?loud? spoken loudly.)
It seems, too, that digital speech is used mainly to refer to
manipulable objects, while analog communication deals with
more subjective items like emotions. In this sense, it may
be that Cetaceans have the ability (using their clicking
apparatus) to communicate digitally as well as analogously.(qtd.
McIntyre 58)
What Warshall is reminding us is that the cetacean?s information
are much more advanced than the information of a human being,
possessing not just one, but two ways to communicate.
The way the dolphin communicates is through sound. Sound is its
primary sense in the ocean. The reason dolphins use sound is that
it is too hard to hunt at night in murky waters because dolphins
are so deep the light doesn?t penetrate the water. Thus, they use
sound to tell if it is loud or soft, fast or slow, high notes or
low notes, short silences or long silences and many other
combinations(McIntyre 133). Dolphins evolved two kinds of voice;
one is for social communication and the other voice is for
navigation and location. The echos they receive are synthesized by
the brain into images and information; for example: distance,
direction, speed, shape, texture, density and the internal
structure of the object. Warshall has written about an experiment
with dolphins:
A trainer taught a dolphin to approach a lit electric bulb.
the dolphin always performed correctly but never looked
at the light bulb. The confused trainer hid the light bulb.
He turned it on and, sure enough, the dolphin swam
towards it. The trainer figured it out: dolphins prefer to
listen-to hear the click of the light switch-rather than look.(qtd.
McIntyre 134)
This proves the theory that dolphins use sonar instead of using
their eyes to see. Their sonar
is like our eyes. They can see anything and tell everything that is
happening around them:
Sonar is a way of ?seeing? with sound. The dolphin sends
out a short click or ping which hits a fish and bounces back.
The Dolphin hears the echo and interprets the size, texture,
speed, location, and other characteristics of the fish from
the echo. An echo can be placed between the outgoing
clicks. In this case, the dolphin interprets the returned
unaltered echo. An echo can also be placed so that it
interferes with the outgoing click. In this case, the
dolphin must interprets the amount and kind of distortion
in the echo.(McIntyre 134)
Bottlenose dolphins have been trained to utilize their sonar to
tell the difference between two metals and the thickness of them.
Dr. Kenneth Norris did an experiment in which a dolphin could tell
the difference between a half inch long gelatin capsule filled with
water and a piece of fish the same shape at twenty feet(McIntyre
134). This is useful to dolphins because they use sonar in hunting
so they don?t chase after the wrong prey:
A dolphin can see detail using his sonar-sight by changing
from low to high frequencies. When sound waves
encounter a fish with great rapidity (high frequency) they
return many more echos. Each echo provides an additional
detail for the dolphin as he forms a sound picture in his
brain.(McIntyre 135)
This is how sound travels in water. Sound is energy.
The way Cetaceans create sound is by a disturbance-an explosion-by
snapping the jaws shut, popping a bubble or slapping the flukes.
This compresses the water and the variations in the disturbance
makes the water ?sound? differently(McIntyre 136). No one knows how
the cetaceans produce their sound, but they are guessing it is the
air that is recycled in the lungs just as with people who play the
saxophone and other instruments like it.
Hearing in water for humans is very hard, but dolphins, who don?t
listen through the ears, have other ways of listening. The way they
hear is through the jaw and the forehead region or melon. The sound
hits the jaw and travels in a thin oil inside the jawbone to the
inner ear drum. The way they hear from the melon is that sound
enters the oil filled melon and passes though air passages to the
inner ear drum(McIntyre 138). The construction sounds in an
oceanarium have been known to be so severe it has killed a dolphin
in the nearby tank. When it rains, the noise in the outdoor tanks
are so painful for the dolphins they leap out of the water just to
escape the sounds like that the rain makes when hitting the water.
The reason why this doesn?t affect dolphins in the ocean is because
they can dive deep enough to avoid the horrifying sound. This is
the way the dolphin and other mammals in the ocean listen to one
another, but it can be painful if the sound is too high in
frequency for the dolphin to take. Nevertheless, dolphins are the
only animals on earth that can hear such high tones and be alright
with it.
These amazing dolphins have been threatened by man for a long time.
Ever since the beginning of time, humans have tried to eliminate
their rivals. First it was the Homo Neanderthalensis; then they
went on to kill most of the elephant species and other large
mammals. In the present century the humans have applied their
knowledge to killing off whales:
The cetacean system appears to be a more integrated and
contemplative one, evolved in conditions where immediate
danger was not so likely as it was for most mammals. It is
ironic that our technology, which developed as an adaptation
to danger, has now presented the whales with dangers for
which their own evolutionary history leaves them quite
unprepared.(McIntyre 36)
Cetaceans evolved so they could figure out what dangers were ahead,
but now that technology has kicked in, it is harder to figure the
dangers out because they are not used to the unnatural forms they
take.
There are chemicals in the water that kills many of the cetaceans
members. People are careless and dump pollutants and other things
in the ocean that are very harmful to the species. One of the first
occurrences of pollutants found in the ocean was Polychlorinated
Biphenyls and DDT?s. Polychlorinated Biphenyls are a very excessive
chemical found in tar and used in lacquers and preservatives of
citrus fruits(Readers Digest Dictionary 141). DDT?s are a powerful
insecticide which are effective on contact( Readers Digest
Dictionary 342).
These pollutants were found on Britain?s coast. John Harwood of
Mammal Research Unit has done tests on a dolphin lying dead on the
shore of Britain:
The tests on stranded dolphins were prompted by the
discovery of a baby Bottlenose dolphin, which was beached
in Cardigan Bay, Wales. The baby dolphin had more PCB?s
and DDT in its tissues than animals from a badly polluted
Wadden Sea off the Dutch coast. ?For the levels to be so
high in an animal so young is very worrying,? said John
Harwood. Some dead porpoises stranded in the same place
also had high concentrations of these pollutants.(qtd. in Mackenzie
22)
If the waters in Britain are this bad, no marine life will have a
chance to live because the pollutants will kill them with in time
of them catching it. The way the dolphins get these pollutants are
from the food they eat. They accumulate them in their blubber and
the toxic pollutants are released when the dolphin has to live off
the blubber when it is ill, pregnant or in stressful times.
Hundreds of dead dolphins were found on the Mediterranean beaches.
These dolphins were killed by a virus similar to the one that
killed 20,000 seals in the north sea. The dolphins died from
pneumonia, because the virus destroyed the brains and lungs which
caused their death. Just as with an outbreak among humans, this is
the dolphins? plague and according to Seamus Kennedy:
The outbreak is the Mediterranean resurrects fears that the
virus could infect all types of marine mammals, including
whales and the endangered monk seal. ?From what we know
about the behaviour of morbilliviruses in terrestrial mammals,
they are extremely virulent and spread rapidly through a
susceptible population.? said Kennedy. Rinderpest, a
morbilliviral disease of cattle, for example, can kill every
animal
in a herd that has not been exposed to the virus before. ?There
is no reason to believe that the virus won?t behave the same
way
in marine mammals.? said Kennedy.(qtd. Mackenzie 22)
This disease is like chicken pox or even something worse, for this
disease can kill. This disease could start out like a common
illness and wind up as an outbreak like AIDS. This epidemic is
spreading north to south from the centre around the Balearic Sea.
Approximately fifty dolphins and other mammals have washed up on
different coast on the east side of the Atlantic ocean. ?We know
that both seals and porpoises are so susceptible to these viruses.
The chances that the monk seals are not susceptible are so slim as
to be non-existent? said Kennedy(qtd. Dolphins in Danger).
This epidemic has spread all the way to the Gulf of Mexico where
thirty-three dolphins have washed up in Alabama and Mississippi.
Kennedy states we think an epidemic is possible:
?Because we find a few animals positive, it means that the
virus is around in a population of high susceptibility,? he
says. He adds that there is no practical way to halt an
epidemic,
and it would simply have to burn itself out. ?If large numbers
die,
at least we know in advance what?s causing it,?(qtd. Dolphins in
Danger 13)
The scientists know where the virus is located, but there is no way
of stopping it because there is no possible way to find a cure
right know. The only hope is that it just goes away.
Researchers have believed that mysterious deaths of thousands of
mammals in Europe and United States have resulted from TBT. TBT is
tributyl tin found in paint on small boats which is used to keep
barnacles from sticking to the hull. This is probably the most
toxic substance ever knowingly introduced to the sea(Pearce 5). The
scientists believed that the porpoises picked up the compounds from
the food. According to Hisato Iwata:
He suspects that butyl tin compounds may be linked to the
mass deaths of several marine mammals populations in North
Atlantic waters since the 1980’s. The animals appeared to
have died from an epidemic morbillivirus, probably triggered
by some unknown agent suppressing their immune systems.
Iwata says that immunosuppression is ?one of the most
representative toxicities of butyl tin compounds.?(Pearce 5)
They think that the butyl tin may have caused the epidemic
morbillivirus which means boats are contaminating the water and
killing the dolphins.
The next biggest problem is that dolphins are being killed by nets
from tuna boats. In 1992 more than a hundred dead dolphins washed
up on the coast of Devon and Cornwell caused by fishing nets. There
were marks of net rope on the dolphin that suggested this scenario.
In Britain the one hundred and eighteen dolphins were the most
mammals killed in their records.
The vets searched for what
happen:
They looked for signs of the highly infectious morbillivirus
that killed tens of thousands of seals in the north sea in the
late 1980’s, and later caused the deaths of hundreds of
stripped dolphins in the Mediterranean. They did not find
any. Nor was there any suggestion that the dolphins had
suffered from a parasitic disease or pollution.(Bonner 6)
This is how they came to the conclusion it had to be nets because
the dolphins didn?t die from any disease, but had marks on them.
The scientists then put two and two together and they figured out
it was the nets. This also tells them that the dolphins were
basically murdered by fisherman just so they could get their
fish.
Thirty to thirty-eight of the dolphins examined had bad marks
around the beak and flipper areas. They also had other marks that
told the examiners that they were caught up in nets. A couple of
dolphins had lost their flippers and other parts because the
fisherman had to sever the parts to get the dolphins free from the
entanglement:
The dolphins died suddenly, with fish still undigested in
their stomachs. The species of fish, mainly mackerel and
pilchard, and the narrow mesh of the nets marks, suggest
that they were caught by purse seiners or pair trawlers,
large boats which ran a net between them up to a kilometre
apart.(Bonner 6)
The fisherman didn?t care what got caught up because they could
have shortened the net and watched where they dropped, but they
only cared about one thing and that was catching the fish.
Dolphins killed by tuna fleets are expected to be less than five
thousand in 1993. In 1992 15,470 died in nets(Marine Conservation
News 22). This is a huge increase and no one cared; they just
wanted to make money.
Six years ago when a heart-breaking video of a dolphin
thrashing in the net of a Panamanian tuna boat was flashed
across the television screens around the world, the solution
for once seemed blessedly simple: Ban the fishing gear and
practices that enmesh the sleek, endearing mammals along
with yellowfin tuna. Congress and the food companies
reacted swiftly. With in a couple of years, the U.S. tuna
market was essentially closed to all but ?dolphin safe?
fish.(Carpenter 71)
This story is why tuna companies should stop fishing with nets and
dragging them all over the water and maybe find a different way to
catch their tuna. Finally, the government came through, but it was
still late because another dolphin had died a horrible death.
Five years ago the Eastern Pacific was a killing field for
dolphins. Over the past thirty-five years six million cetaceans
were killed from the tuna boat?s nets. The dolphins were caught in
the nets because tuna swim right underneath the dolphins and this
is how the dolphins get captured. Tuna boat captains now have
special orders and hopefully this might work:
Before a net is hauled in the captain backs up the boat,
allowing
one end of the net to dip below the sea surface opening up a
escape channel for trapped dolphins. Skippers also use a
special
net with a panel of fine webbing to prevent dolphins from
snagging their beaks and drowning. Moreover, each tuna boat
is granted an annual dolphin kill quota. If a skipper exceeds
his
limit, he must stop fishing on dolphins for the year, and the
excess
is deducted from his allotment for the next year.(Carpenter 72)
This is a good technique, but they shouldn?t kill any dolphins. The
new quota should read: if they kill one dolphin they will lose
their boating license and be fined heavily. With the safe nets,
they should have no problem keeping dolphins alive. The government
should also only let a certain amount of boats to tuna hunt and
they should all be professional?s. That way we will have no dolphin
killing.
Tuna boats have tried several methods of keeping dolphins away from
nets. The first method is by bombing and the second is using fake
fish. The bombing procedure works like this. First they find a
school of dolphins and then a helicopter or speed boat drops a seal
bomb to disorient the dolphins. This method allows the fisherman to
net both dolphins and tuna and once they are caught up the
fisherman drop another bomb to chase the dolphins out the other end
of the net. However, environmentalists say ?the dolphins get caught
up in the nets still.?(Anderson 19) Congress finally has done
something right:
In the late 1988, the U.S. Congress banned the use of
explosives more powerful then seal bombs, which were
exempted from the legislation pending further studies. Last
November, the national fishery service concluded that no
explosives should be detonated within one and a half feet
of the dolphins(Anderson 19).
The Fisheries Service stepped in and told the boats what to do
because the government was too scared.
The other method works like this. The plastic devices reflect the
dolphin?s sonar signals and stop them from swimming into the
nets:
Dolphins and porpoises forage for food with the help of sonar.
Like bats, they send out sound waves and make sense of their
environment beyond the range of their sight from the echos they
receive back. ?It?s as if the animal has a spotlight on top of
its
head, a bit like a miner?s lamp.? says David Goodson., but
fishing
nets are too fine to reflect the sonar. ?Essentially, the net
is
acoustically invisible to the dolphins.(Coghlan 18)
If they can find a way to make the nets sonar built, then the
dolphins will steer away from them and there will be no dead
dolphins. The design of the experiment is a lightweight ball: ?The
curvature of the inner surface is critical and must be exactly
right to give the required reflection from any angle
approached?(Coghlan 18). The dolphins are supposed to swim over the
nets, but instead they swam around them and then after it was clear
they went back to the original course after they bombarded it with
sonar. Goodson says ?a much larger scale test is now required to
optimize the reflection design and spacing(Coghlan 18). The only
hold back for this project is the money needed for the research and
without further support this idea will fail.
Humans have directly caused some of the dolphin?s deaths too. The
humans alone have done this without any weapons, chemicals or nets.
According to C.A.L.M(Department of Conservation and Land
Management):
Young dolphins at Monkey Mia in Western Australia are
dying because their mothers have become dependent on
food handed out by park rangers to entertain tourists. The
Dolphins nursing from hand fed females, are malnourished
and vulnerable to disease and attack by predators.(Anderson 5)
The rangers are killing the dolphins and the tourists think it is
fun. If the dolphins become weak then they will die from sharks and
other enemies because they are so weak they can not fight
back. In 1975 tourists were feeding four female dolphins and only
two of these dolphins are still alive. The females produced
seventeen offspring and only five remain. The mortality rate was
seventy percent since 1986(Anderson 5)
Even sometimes dolphins kill their own kind. Nineteen healthy
dolphins were stranded on the beach and died because they followed
their leader. Every one of the dolphins were healthy except the
male leader, the one they followed. Paul Jepsen says ?Sick
cetaceans often beach themselves?(qtd. Anderson 5). This is just
like a cult doing what ever the leader does. According to
Jepsen:
There are three theories about why groups of dolphins
become stranded on beaches, he says. ?It may be through
disease, or because they chase fish inshore or because of
some sort of navigational error–perhaps because their echo
sounding systems do not spot gently shelving beaches.? The
autopsies showed that none of the dolphins had been eating
fish immediately before they die.(qtd. Anderson 5)
This is the fault of the dolphins, even though they are supposed to
be the smartest mammal then why are they doing this to
themselves.
After all the killing of dolphins by tuna boats, the government has
finally made some rules against these fishermen. Tuna companies
have agreed that ?they will no longer sell tuna caught by methods
harmful to dolphins?(?Tuna w/o Guilt? 63). The companies will put
out a label on all cans that will say ?Dolphin Safe.? According to
Senator Joseph Biden:
The Tuna company will put a DOLPHIN SAFE logo on its cans,
and may have to charge ?a couple of cents more? to account for
higher costs, O?Reilly said. The dolphin-free promise was
matched
on the same day by the other two major canners, Bumble Bee
Seafood and Van Camp Seafood which sells Chicken of the Sea
brand. Environmentalists responded with glee. ?It was an
incredibly
responsible action.(?Tuna w/o Guilt? 63)
The canners have agreed as well that ?They will no longer accept
tuna caught in the region, unless it has been harvested without
saving the dolphins as well?(?Tuna w/o Guilt? 63). When they had
announced that the tuna fish would be made dolphin free, they said
?It symbolized the triumph of ecological values that not only can
not be measured in dollars and cents, but have no obvious human
benefit at all, this ones for the dolphins?(?Swim With the
Dolphins? 76). Heinz made the first move to ensure tuna fish to be
dolphin safe. Following them were other companies. Heinz did this
in concern for customers and in taking this step, it received post
cards and letters from concerned school children. Ted Smyth says:
?Hopefully in a few years the safest place for tuna will be
swimming
underneath a dolphins.?(?Swim With the Dolphins? 76) If a law is
passed that tuna boats can not net around dolphins then tuna will
not have anything to worry about because they swim with the
dolphins and no one will be able to get to them.
Health experts urge Americans to live longer by eating more fish,
but environmentalists warn that netting tuna had already killed
80,000 dolphins. There is concern for this because they are the
most intelligent creature next to humans. Now the tuna boats sail
behind the banner? We Love Dolphins.? The problem is that tuna love
dolphins too, and love to swim with them. When the boats throw the
nets around the dolphins, they just hope to find tuna below, not
realizing the danger they are causing to other creatures besides
the dolphin:
Dolphins are not yet completely safe. Giant fishing vessels
towing 30-miles-ling drift nets strip mine the sea of both
mammals and fish. Their effectiveness is so complete that
The United Nations has called for an end to their use. And
then there?s pollution. When half the Bottlenose dolphin
population on the U.S. mid-Atlantic coast died, the government
suspected a natural red tide was to blame. But many scientists
wondered whether PCB?s found in the dead creatures, often at
levels fifty times higher then the levels allowed in fish, had
weakened them first.(?Dolphins Get a New Reason? 14)
Finally the government understands that the nets are very dangerous
to the dolphins and other cetaceans in the ocean. Now what the
dolphins have to worry about is PCB?s, and if they get attacked by
anything then they will be defenseless because they will be so
weak.
Another problem the dolphins have to face is captivity: ?Hearts are
won over when these marine mammals perform, but many critics
believed that it is cruel to keep them in captivity?(Riley 58).
Laws were passed in South Carolina banning any public display of
captive dolphins and whales and in Australia their capture and
display has been ban since 1988. The Miami Dolphins football team
has a dolphin that is in a tank so it can perform for the fans
during halftime. Lawsuits were filed against New England Aquarium
over treatment of the dolphins.
Whatever the future holds, the special relationship that has
existed between the dolphins and humans since the time of
Homer will continue. Even Scientists trained to observe life
with strict objectivity, recognize the human urge to find ?a
kindred
spirit? in dolphins. O? Barry learned that happiness in life is
the
journey itself, not some place you arrive at. Dolphins live that
way
every day. (Riley 67)
Dolphins and man have always been close and will be like this for
years to come. Dolphins live
life in happiness because they don?t realize the danger people
cause them.
Dolphins are fascinating creatures which people already know, but
now people are understanding them better. We have lost a lot of
dolphins over many of years and hopefully people, fishing boats,
and chemical plants will watch what they are doing because they are
destroying a species that one day could save our lives and be a
valuable source. Look at what the dolphins did for the navy during
wartime. They helped guide the ships through mine fields and
spotted the enemies ships and other things to help the U.S. in the
war.
Maybe Congress or even the president will pass a law that prohibits
tuna boat fishing unless they can come up with a way not to kill or
hurt the dolphins. There are still many dangers out in the ocean
that are killing dolphins and hopefully in the future we will be
able to find them all and cure them so not another single dolphin
will die. Remember dolphins are mammals and they are very close to
us so we should protect them as we protect our own species.
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1994: 5.
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Pain, Stephanie. ?Dolphins Virus Threatens Last Remaining Monk
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Scientist 13 Jan. 1996: 5
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