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Tuesday Tetrapod: Orcinus orca

Posted by tigerhawkvok on March 02, 2010 23:56 in tuesday tetrapod

Now, let's take a turn to the water, and have a Tuesday Tetrapod on Orcinus orca, or the Orca ("Killer Whale").

O. orca

O. orca. Photo CC-BY-NC-ND by Flickr user SteveWhis.

One of the few common extant animals referred to by its specific name, orcas are the second most widely distributed mammal on the planet, after humans. Specifically:

O. orca

Orcas CC-BY-ND by Christopher DiNottia

Although killer whales occur worldwide, densities increase by 1-2 orders of magnitude between the tropics and the highest-sampled latitudes in the Arctic and Antarctic (Forney and Wade 2006). Killer whales tend to be more common along continental margins; however, there is some variation in this general pattern that appears linked to ocean productivity. Killer whales appear to be less common in western boundary currents, such as the Gulf Stream or the Kuroshio than in more productive eastern boundary currents, such as the California Current. Known areas of locally higher density often coincide with greater oceanographic productivity (e.g. off Argentina).

O. orca is technically a type of dolphin, a member of delphinidae, and possibly a complex of up to five species (but probably a combination of species, subspecies, and races). Currently, they are grouped as "populations" of transients, residents, and offshore, primarily differentiated by diet and behaviours with minor morphological differences.

Orcas are large, and commonly seen in water shows. They age at a rate similar to humans, with sexual maturity reached around 15 for females, and reaching up to 90 in age.

The orca is IUCN "data deficient", due to possible specific/subspecific splits and that certain populations are experiencing a 30% population drop over 30 years, while others maintain a stable population.

There is a gigantic repository of information on Orcas available — it is a Wikipedia featured article and many other resources are available online.

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Freedom Mentor

Freedom Mentor | 03/03/2015 11:36

Tuesday Tetrapod: Orcinus orca | The Dichotomous Trekkie 2.0

Freedom Mentor

Freedom Mentor | 03/03/2015 11:34

Tuesday Tetrapod: Orcinus orca | The Dichotomous Trekkie 2.0