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Orca (Orcinus orca): Difference between revisions
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== Hunting == | == Hunting == | ||
Orcas are precise and efficient hunters that use different strategies depending on their prey and region<ref name=":3">[https://wearesonar.org/2015/06/08/three-amazing-orca-hunting-strategies/ Three Amazing Orca Hunting Strategies] We Are Sonar</ref> | Orcas are precise and efficient hunters that use different strategies depending on their prey and region.<ref name=":3">[https://wearesonar.org/2015/06/08/three-amazing-orca-hunting-strategies/ Three Amazing Orca Hunting Strategies] We Are Sonar</ref> They feed on over 140 species, including great white sharks, which they rip open for their livers and hearts¹. They can flip the sharks over to induce a state of paralysis and make them easy to eat.<ref name=":3" /> They can also come ashore to hunt seals and sea lion pups, hiding their dorsal fins and beaching themselves.<ref name=":3" /> | ||
Some Antarctic orcas use the cunning tactic of regularly hunting in packs and making waves to wash seals off floating | Some Antarctic orcas use the cunning tactic of regularly hunting in packs and making waves to wash seals off floating ice. These hunting techniques are almost ritualistic and are passed down from generation to generation. | ||
== Distribution and habitat == | |||
Killer whales are found in all oceans15. While they are most abundant in colder waters like Antarctica, Norway, and Alaska, they are also found in tropical and subtropical waters16. The most well-studied killer whale populations occur in the eastern North Pacific Ocean17. Resident killer whales have been seen from California to Russia19. Offshore killer whales have the largest range of any community, and often occur more than 9 miles offshore20. They are not, however, exclusively “offshore”, as they are sometimes seen in coastal nearshore waters21. Transient killer whales also occur throughout the eastern North Pacific, and are often seen in coastal waters18. Their habitat sometimes overlaps with Resident and Offshore killer whales22. | |||
== Reproduction and lifespan == | |||
The average lifespan for male killer whales is about 30 years, but they can live up to at least 60 years23. Females typically live about 50 years, but can live up to at least 90 years in the wild24. | |||
Females reach sexual maturity when they are between 10 and 13 years old25. They are typically pregnant for 15 to 18 months and give birth to a single calf26. Calves nurse exclusively for at least a year, but remain in close association with their mother for the first two years27. There is no distinct calving season, so birth can take place in any month28. The birth rate for killer whales is not well understood. In some populations, birth rate is estimated at every 5 years for an average period of 25 years29. Killer whales, beluga whales, narwhals, short-finned pilot whales, and humans are the only known species that go through menopause30. | |||
== Conservation status == | |||
All killer whales are protected under the [[Marine Mammal Protection Act 1972|Marine Mammal Protection Act]] (MMPA) in the United States. Only two populations receive additional special protections under federal law: | |||
* Southern Resident Distinct Population Segment (listed as endangered under the Endangered Species Act) | |||
* AT1 Transient stock (designated as depleted under the MMPA). | |||
== Threats == | |||
* Entanglement in fishing gear | |||
* Prey depletion | |||
* Chemical contamination | |||
* Oil spills | |||
* Noise disturbance | |||
== Captivity == | == Captivity == | ||
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The practice of keeping orcas in captivity is harmful to the animals due to the separation from their familial pod during capture, and their living conditions and health in captivity.<ref name=":5" /> | The practice of keeping orcas in captivity is harmful to the animals due to the separation from their familial pod during capture, and their living conditions and health in captivity.<ref name=":5" /> | ||
== See also == | == See also == | ||