By: Misha Busch & Ben Barber Orca: The Killer Whale By: Misha Busch & Ben Barber

Orcinus Orca The Orca is from the order Cetacean, and part of the Dolphin family. Killer whales live in family groups called pods. Three types of pods have been described: Resident pods: which remain in one location year round instead of migrating. Found mostly in the North Pacific ocean. Usually sized from 5-50 orcas. Transient pods: travel around, don’t stay in one spot. They are more of a loner pod ranging in size from 1-5 orcas. Offshore pods: Are seen only in outer coast waters and not much else is known of them.

Location Orcas can be found as far as Antarctica, up and down the west coast, and other cold water regions. Although orcas can be found in all oceans, they seem to prefer coastal waters and cooler regions like Antarctica, Norway, and Alaska.

Life Span Orca males typically live for about 30 years, but can live as long as 50-60 years. Orca females typically live about 50 years, but can live as long as 80-90 years.

Behavior Orcas are highly social animals, needing daily interaction with pod members. Orcas depend on underwater clicks, whistles, and pulsed calls to communicate and find food. Researchers have identified four basic behaviors that are exhibited by orcas; foraging, resting, traveling and socializing. However, so much of orca life is hidden beneath the water that it is extremely difficult to label all activities. Orcas in British Columbia spend a great deal of time at a particular beach where they rub their bodies on smooth round pebbles at the bottom of the cove. No one really knows what purpose this activity serves, yet the whales are extremely secretive here and will stop if they are interrupted by humans. They guess it is pleasurable to the orcas though. Happily, this area, Robson Bight, has declared an ecological preserve that is off limits to boats and hikers.

Who Feeds On It The orcas are top predators and have no threats to them other than humans. The killer whale is also known as the Wolf of the Sea. Some of the baby orcas have been eaten by very large sharks before, because they strayed to far from their mothers, but this is happens very rarely.

Feeding Behavior Orcas feed on many types of food varying from fish to sharks, depending on the type of orca. Resident pods in the Pacific Northwest spend on average 65% of their time foraging for Chinook salmon, their favorite food. Yet they can spend as little as two to three hours foraging when fish are plentiful. They also like squid. Foraging is defined as any activity associated with feeding or searching for food and is understandably the most common orca behavior. Obviously, declines in fish stocks and the disruptive influence of boat traffic force these whales to spend proportionately more time in foraging mode. This reduces time spent resting or socializing and may account for the higher mortality rates seen over the last four years.

Feeding Behavior Continued Transient pods never touch a fish or squid, but prey exclusively on seals, sea lions, porpoises, dolphins, and other large whales. Offshore pods eat mainly sleeper sharks (smaller sharks). Because offshore pods eat mainly sharks, their teeth get worn down almost to the gums because shark meat is so tough

Reproduction Orcas give birth to one calf at a time every 3-10 years. Their pregnancy lasts 16-18 months. And babies nurse for the first year. They start breeding around the young age of 14-15 years old. Almost half of all the babies born die within the first year. Thus concluding that female orcas only have about 4-6 babies in their lifetime.

Reproduction Continued Female orcas mate every 3-7 years in a cycle known as polyestrous. (having several estrus cycles during a breeding season). Female orcas are the leaders of their pods and never breed with another orca from their pod to avoid interbreeding, but with different pods. When it comes to the males finding a mate, they become very aggressive over the females and tend to fight, which is why there are many killer whales that have scars on their bodies. However, males do not mate for life. They do, though, stay with their mothers for life.

Environment Impact Orcas can have a profound impact on the marine food web. Thousands of sea otters went missing from the Aleutian Islands during a ten-year period. Some scientists believe that the 40,000 missing sea otters could have been removed (eaten) by as few as four orcas.  These changes are a result of the harvest of the great whales during the whaling era. The hypothesis predicts that once the whalers killed the great whales, the transient orcas switched prey to seals, sea lions and sea otters, a phenomenon referred to as a trophic cascade. (Trophic cascades are indirect interactions that can control entire ecosystems). Trophic cascades occur when predators limit the density and behavior of their prey and then survival of the next lower trophic level grows extremely large.

Environment Impact Continued Now that the sea otter population is a fraction of what it once was, the sea urchin population, a favored sea otter food, is booming, eating the marine kelps and altering the near-shore ecosystem. This is referred to as top-down control, (limitation of the amount of a population by consumers), and is an important factor in altering marine ecosystems. Orcas are at the top of the marine food web, so they are more susceptible to contaminants than are many other species, due to biomagnification and the increase of contaminants in the marine ecosystem. Biomagnification causes the concentrations to become so high that they impair the orcas’ immune and reproductive systems or kill orca offspring.  Humans cause this whole thing to happen by originally removing the orca species.

Human Impact Humans are the only problem affecting orcas, due to the fact that they are the “wolf of the sea”. Humans have harmed orcas by; commercial hunting (for meat and used to be for oil). Live capture for leisure display Culling (killing a portion of the pod to control populations). Loss of food due to overfishing the oceans. Toxic exposure (due to marine toxic waste dumps). Underwater noise (due to ships using sonar). And surface impacts, like collision impacts with boats, whale watching boats that get to close and stress the whales leading to them not feed, and exhaust emissions in breathing pockets (which is when there are so many boats on the water that there exhaust stays on the surface of the water and when the whales come up for a breath they breathe it in).

What You Can Do Orcas are very intelligent animals and deserve to be free. When going whale watching please only go with people that keep their distance to protect the whales. And don’t visit marine parks that support the capture of orcas.

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