Orca (Killer Whale)By:Jonathan Mendes


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Classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Suborder: Odontoceti
Family: Delphinidae
Genus: Orcinus
Species: O. orca


Introduction and DescriptionThe orca or "killer whale" is a toothed whale that actually belongs in the oceanic dolphin family. (5) The Orca is considered to be a mammal and needs air to breathe. There have been many theories as to why the orca are called killer whales. Recent scientists believe the orca is called the killer whale because of their extremely powerful jaws and teeth, that allow them to eat other animals. The orca's jaw is so powerful, that the can actually bite an animal in half ripping their bodies apart before eating them. The killer whale also get its name from it wolf like hunting patterns and their extreme diets. Early sailors actually observed orca preying and eating other whales, something that had been seen by man before. (5)
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Orca body compared to an average male human.




The build of an orca tends to be based on whether the orca is a male or a female. A male orca will typically range anywhere from 20-26 ft. long and weigh on average anywhere from 8,000-12,000 lbs. (8) Females on the other hand tend to be much smaller, ranging anywhere from 16-23 ft. long and weighing anywhere from 3,000-8,000 lbs. Some male orca's, although it is very rare, have been known to grow up to about 28ft. long and weigh as much as 22,000 lbs. (8) The average male orca lives about 30 years, where as the average female orca lives to about 50 years old. Some male orcas can live to about 50-60 years old, while some females can live to about 80-90 years old, although both cases seem to be very rare.





Habitat and Population
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The blue would indicate active orca life.

The orca have very adaptive bodies which allow them to live in any ocean around the world. Orca are found in all of the oceans, and can live anywhere from the frigid arctic waters, to the warm waters of the Caribbean Islands.(4) A rough global estimate has estimated that there are an absolute minimum of about 50,000 orcas living throughout the world. About 50% of the orca population live around Antarctica, while a little less than 20% of the orca population living in the tropical water of the Pacific Ocean. The remaining 30% of the orca population is said to be spread out throughout the world.(4)

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Different shaped and sized dorsal fins, in a pod of orca.






Dorsal Fin
The dorsal fin is the fin that sticks out from the top of the orcas body. The dorsal fin can grow up to about 6 ft. length for males and slightly smaller for females, and can be extremely sharp depending on the orca. (9) Each dorsal fin is different in both shape and size, as no two orca have identical dorsal fins. The purpose of the dorsal fin is to protect the orca from rolling over on its side, and helps balance the orca as they swim. Another purpose of the dorsal fin, it to help the orca make sharp or sudden turns while chasing prey.(9) Without the dorsal fin it would be much harder for orca to hunt down their moving prey, because they would not be able to turn from side to side as quickly.


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A baby orca swimming next to it's mother.

Baby Orca
Female orca tend to have babies, on average, once every ten years, although it is not uncommon to find some females giving birth once every 3-5 years.(2) When a female orca gives birth to a baby orca, the mother must help the baby to immediately swim to the surface to get its first breathe of air. Typically, the umbilical cord fails immediately after the mother has given birth to the baby. Typically new born orca are about 8 ft. long and weigh somewhere between 250-400 lbs. New born males and females are very similar, and only start to show significant size differences a few years after birth. Female orca and their young have a very unique relationship unlike many other marine species. (5) Mothers feed their young with milk for quite a few months, until the baby have learned how to hunt on its own. Baby orca also stay by their mothers side for about one full year before they become independent and swim alone. (5)






Diet

Orca tend to have a very wide variety, when it comes to diet, and most of what orca will feed on just depends on the location. Orca eat many different kinds of fish (over 30 different species) that can vary anywhere from tuna and salmon to different species of whales and sharks. Orca also tend to prey on seals, sea lions, turtles, squid, sharks, other whales, and different types of bird species such as penguins and gulls.(6) Orca are so massive and strong, that they can swallow small sea lions and seals whole or they can shred their bodies with very minimal efforts. Orca have also been observed to play with their food before eating it. Orca also swim right onto the shore line of a beach to eat some mammals (such as deer) or seals that are out of the water, and this behavior can be very dangerous for the orca as they can easily get stuck on the shore line if their timing is off. (6) There have been very little wild human attacks by orca, and wild orca are usually not a threat to humans who are in the ocean.


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An orca preying on a group of penguins.

















Orca Behavior

Orca have very complex and sophisticated social structures, and scientists have explained that only humans and elephants have more complex social structures than the orca do. One unique fact about the orca social structure, is that in some cases there are four generations of orca females living together in the same "pod" or social structure. Orca form small groups or pods, in which they will travel, hunt and mate together. (2) Most orca will combine their pods with other pods forming clans which would be consider a few orca pods that have decided to live and travel together. Lastly, after clans have been created, these then combine with other clans and form what are known as orca communities. These communities become very large groups of orca that can group up to over 100 orca living together under one social structure. When a community of orca is formed, none of the orca tend to usually leave this community unless they decide that they need to mate with someone outside of their community. Orca also hunt in large groups, and can hunt with a group that ranges from just 2 orca to over 50 orca at a time. (2) Because of their group like hunting, orca have gotten the nickname of "wolves of the sea". (5) Orca use very sophisticated and intelligent hunting methods, one of which is shown the video to the right. Scientists believe that due to the sophistication of the orca and their high intelligence levels, orca should not be taken into captivity and used for entertainment purposes by humans.




Captivity and Attacks
Orca are known to be one of the most trainable animals in
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An orca performing a trick at a theme park.
animal kingdom, due to their levels of intelligence. Starting around 1976, orcas were beginning to taken captive for entertainment and attractions at theme parks such as sea world. Their easy train ability as well as playful behavior and high intelligence level have made orca a very popular attraction at theme parks for over 30 years. Orca have been trained to do many tricks such as jumping up causing a huge splash to hit the crowd, or waving their tails as to be saying hello to the crowd and even swimming along side with humans. Some orca are even allowed to interact with the audience, as members of the crowd are allowed to come down and feed or pet the orca. One major downside that scientists have found with captive orca, is that their life expectancies are much lower wild orca. Males tend to only live into their 20's when they are held in captivity, and studies have shown that most of these orca die due to high levels of stress and loneliness because they have been held in captivity for so long.


There have been some recorded acts of violence performed by captive orca in the last ten years.(7) One captive killer whale named Tilikum has killed three different people in his lifetime.(3) Scientists believe that these aggressive orca act out violently against their trainers, because they have very high levels of stress. It is unclear by experts at this time whether these captive orca are deliberately attempting to cause harm to their trainers or if they are just unfortunate accidents.(1) Wild orca on the other hand typically don't attack or even try to get close to humans and their have been very little known and recorded wild human attacks by orca.
The video below describes how Tilikum killed his last victim in 2010. (11)









Source1.http://www.csmonitor.com/USA/2010/0225/Sea-World-tragedy-How-common-are-killer-whale-attacks
2.http://animals.nationalgeographic.com/animals/mammals/killer-whale/
3.http://articles.cnn.com/2010-02-24/us/killer.whale.trainer.death_1_killer-whale-trainer-seaworld-employees?_s=PM:US
4.http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/killerwhale.htm
5.http://marinebio.org/species.asp?id=84
6.http://www.iucnredlist.org/apps/redlist/details/15421/0
7.http://www.csmonitor.com/USA/2010/0225/Sea-World-tragedy-How-common-are-killer-whale-attacks
8.http://www.seaworld.org/infobooks/KillerWhale/physchkw.html
9.http://www.acsonline.org/factpack/KillerWhale.htm
10.http://www.youtube.com/watch?v=DWsN63PRCW8
11.http://www.youtube.com/watch?v=p3xmqbNsRSk&feature=related
12.http://www.youtube.com/watch?v=qz_SHumjgPQ