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“Killer Whales: Gentle Giants, or Viscous Killers?”
Killer whales are an important subject of mythology for many
indigenous peoples, especially the Native Americans of the Pacific
Northwest. The whales have not been hunted extensively by humans,
although they have been hunted by some shore whaling operations, and
some individuals have been taken as aquarium show animals from the
waters around the Pacific Northwest and Iceland. Killer whales are
perceived by many near-shore fishermen to be in competition with human
fishing activity (Anheiser Busch 1).
The killer whale, or Orcinus orca can be found worldwide in all seas
from both tropics to Arctic and Antarctic oceans. They are one of the most
well known whales because of the captivity of Shamu at Sea World and the
other studies that are widely publicized (2). The male killer whale has an
average length of 6.7 to 7.0 meters and can weigh between 4,000 to 5,000
kilograms (Knight 5). The female killer whales are smaller having a length
of 5.5 to 6.5 meters and weighing 2,500 to 3,000 kilograms. They have 10
to 12 pairs of large conical teeth in each jaw (Evans 12).
Their coloration is very striking. They have black on the back and
sides and a white belly that extends as a rear-pointing lobe up the flukes
and less markedly near the head, and around the throat (15). They are also
white on the chin and underside of their flippers with a distinctive,
conspicuous white oval patch above and behind each eye. This coloration
varies depending on regional variations. Killer whales can have indistinct
gray saddles over their backs just behind their dorsal fin (Evans 16). This is
called countershading. Countershading enables the whales to be
camouflaged from their prey (Wolfe lecture). They have a stout
torpedo-shaped body with a conical-shaped head. Their flippers are large
rounded and paddle-shaped with a centrally-placed dorsal fin. The dorsal
fin is sickle-shaped in adult females, but very tall and erect in adult males.
There are some variations in morphology between regional populations but
vocal dialects vary more between pods than geographically. There is no
exact known population size. But the largest numbers are in the Antarctic
where the population is estimated at more than 160,000 (Wheelock Colege
1).
Killer whales may be solitary or live in groups of 2 to more than 50
animals. Food items include squid, fish, skates, rays, sharks, sea turtles,
sea birds, seals, sea lions, walrus, dolphins, porpoises, and large whales
such as fin whales, humpback whales, right whales, minke whales, and
gray whales. They are even known to attack the sperm whale and blue
whale. On the Atlantic coast of South America, as well as on islands of the
Indian Ocean, killer whales have been observed lunging through the surf
and coming right onto the beach in pursuit of elephant seals and sea lions
(Holt 17). After such an attack the whales have to wriggle and slide back
into depths adequate for swimming. In captivity, killer whales eat about 45
kg of food per day but free ranging animals probably require much more.
Although these are obviously proficient and voracious hunters, killer whales
are not known to have ever attacked a human (Evans 123).
At sea they are usually seen in pods of 5-20, although up to 150
have been seen together at one time. Large groups probably consist of
several pods which have temporarily aggregated. Pods themselves appear
very stable for many years, with little emigration or immigration (124).
They are highly cooperative and the group functions as a unit when
hunting, making these delphinids extremely efficient predators. Groups
usually contain adults of both sexes but sometimes females with young will
form their own groups (125).
Although much research has focused on killer whale pods around
Vancouver Island and on the mainland coast, very little is known about the
whales often found in the Queen Charlotte Islands, known as offshore
killer whales. This separate population of killer whales appears to share
similar behaviors and the fish-eating lifestyle particular to resident whales
but appear to maintain an offshore distribution and are unique in their
vocal dialects — indicating they're unrelated to any transient or resident
pod. Offshore whales tend to be seen in large groups of 30 to 60, and are
seldom seen in protected coastal waters. At present, there are limited
details concerning the offshore population's range, social organization or
life history. However, we hope that it will be possible to fill in many of these
gaps in the future, and to determine if and how these offshore whales
might be related to the well-known inshore resident and transient
populations (Wheelock College 15).
The reproductive habits of these whales are poorly known. The males
may mate with more than one female and mating may occur throughout
the year, although most calves seem to appear in autumn or winter in
shallow waters. The female gives birth to a single calf 16 or 17 months
after mating. The calf is nursed for 14 to 18 months (Anheiser Busch 16).
Calves are approximately 2.4 m long at birth and reach sexual maturity
when 4.9-6.1 m in length. Groups of killer whales seem to be remarkably
stable, with males and females staying in their natal pods, or groups, for
life. Consequently, researchers believe that, to keep inbreeding to a
minimum, mating does not occur between members of the same pod as
often as it does between members of different pods (Holt 12).
Like the complex social organizations in which they live, killer whales
also have very distinct and complex methods of communicating. Vocal
variations of resident, transient and offshore killer whales have identified
distinctive dialects that are used to recognize particular groups of whales
and relationships between groups and populations (Knight 10).
Killer whales use echolocation to gather information about their
surroundings. They send out high-frequency clicks that bounce off prey
and other objects and they interpret the returning echoes. Killer whales
communicate by means of rapid-fire click trains that sound like rasps and
screams, although when they are on the prowl for marine mammals, which
have acute underwater hearing, they can be silent for hours at a time.
Other sounds such as squeaks, squawks and screams are sounds used for
social contact within and between groups of whales. These sounds, which
are specific to a single group of whales, make up each group's dialect (Holt
5).
Killer Whales, like all animals, have their own specific niche, or job in
their ecosystem. They are top predators. Their job is to weed out and
hunt the sick or weak animals. This process allows a species to thrive. If
the sick and weak are allowed to live, then reproduce, they pass on their
sickness or weakness to their young, thus making the entire population
weaker. This demonstrates “Nature’s Multiple Choice Question: a)Move
b)Adapt c)Die.” These whales are believed by some scientists to have
evolved from land mammals (Wolfe Lecture).
We do not use these whales for any purposes like food or medicine,
although they used to be hunted along with humpback whales and Pseudo
Orcas, or false Killer whales for oil and blubber. We do however, capture
these whales to perform in Marine Theme Parks, and in some, like Sea
World, we use them to educate the public (Killer Whale 8). Killer whales
have no natural enemies, their only enemy is man (Wolfe).
I chose this animal because ever since I was little, I have been
fascinated with these whales. I remember my first time going to Sea World
when I was 7 years old. I saw this giant creature doing all sorts of tricks
and I was mesmerized. Back then you didn’t learn about the whales, you
just watched the tricks. Now, over the years, the shows have become more
and more focused on education. I wanted to learn more, which is why I
chose this mammal.
Man doesn’t know enough about these whales. They are still
fascinating animal lovers, especially since the making of the movie “Free
Willy”. Millions of people visit parks like Sea World ever year, and learn
more about these beautiful creatures. We must continue to study them in
their natural environment and learn as much as we can.
Bibliography
Works Cited
Anheiser Busch. “Animal Resources.”
http://www.SeaWorld.org/infobook.html. 1998.
Evans, Peter. Whales & Dolphins. Facts On File. New York, NY. 1987.
Holt, George. “Orca.” http://thewildones.org/SFC/Seana/george.html.
1998.
Knight, Tim. “Killer Whale Info and Pictures.”
http://www.selu.com/~bio/wildlife/
mammal/whale/killerwhale01.html. 1997.
Wheelock College, Boston. “WhaleNet.” http://whale.wheelock.edu/.
1997.
Wolfe. Oceanography class Lectures and Handouts.
Word Count: 1373
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