Killer whales, four species?


This video says about itself:

Dec 10, 2012

The killer whale (Orcinus orca), also referred to as the orca whale or orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas. Killer whales as a species have a diverse diet, although individual populations often specialize in particular types of prey. Some feed exclusively on fish, while others hunt marine mammals such as sea lions, seals, walruses, and even large whales. Killer whales are regarded as apex predators, lacking natural predators.

Killer whales are highly social; some populations are composed of matrilineal family groups which are the most stable of any animal species. Their sophisticated hunting techniques and vocal behaviors, which are often specific to a particular group and passed across generations, have been described as manifestations of culture.

The IUCN currently assesses the orca’s conservation status as data deficient because of the likelihood that two or more killer whale types are separate species. Some local populations are considered threatened or endangered due to prey depletion, habitat loss, pollution (by PCBs), capture for marine mammal parks, and conflicts with fisheries. In late 2005, the “southern resident” population of killer whales that inhabits British Columbia and Washington state waters were placed on the U.S. Endangered Species list.

From Wildlife Extra:

Possible fourth species of Killer whale identified

New technology supports evidence of multiple species

June 2013. In April 2010, scientists reported finding strong genetic evidence supporting the theory that there are at least three species of killer whales (Orca) in the world’s oceans. New evidence suggests that a fourth species, type D, has been identified.

Type D

The first possible sighting of the new ‘Type D’ was in 1955 when a pod of unusual-looking orca stranded on a beach in New Zealand. Recent photographs of similar orca from the southern Indian Ocean reveal that they have a very small white eye-patch and bulbous forehead. Analysis of a skeleton from the 1955 stranding, now in a museum in Wellington, indicates that ‘Type D’ is highly divergent from all previously genetically sequenced killer whale forms. The estimated divergence was as long ago as 390,000 years, the second oldest split within the killer whale phylogeny.

Very different behaviour patterns

Scientists have suspected for some time that there was more than one species of killer whales because of differences in behaviour, feeding preferences and subtle physical features.

The following killer whales were recognised as separate species in 2010:

Type-B “pack ice killer whale” from the Antarctic. Note the large eye-patch and two-tone gray color pattern. This type specializes in hunting seals, which are often on the ice and need to be knocked off the ice by the whales before they can be caught.

Type-C “Ross Sea killer whale” from the Antarctic. Note the narrow angled eye patch. These are the smallest of the 3 Antarctic types and they eat fish that are found primarily under the ice pack, so they follow leads deep into the ice as it breaks up in the summer months.

Type-A killer whale from the Antarctic. Note the striking black and white colour pattern. This type is found in open water areas and feeds primarily on other cetaceans (whales and dolphins).

NE Pacific Transient killer whale in Alaska. Note the typical black and white colour pattern and eye-patch, similar to Antarctic Type A killer whales (left), but genetically distinct. The Transients are known to feed on all types of marine mammals, including other whales, dolphins, and seals and sea lions.

139 killer whale samples analyzed – Several species identified

In all, tissue samples from 139 killer whales were analyzed. Samples came from killer whales found in the North Pacific, the North Atlantic and oceans surrounding Antarctica. As a result of the study, two types of killer whales in the Antarctic that eat fish and seals, respectively, are suggested as separate species, along with mammal-eating “transient” killer whales in the North Pacific. Several other types of killer whales may also be separate species or subspecies, but additional analysis is required.

These findings also highlight the value of natural history museum collections and new technologies to investigate the taxonomy of rare, cryptic or difficult to access species.

Read more information in the journal Polar Biology.

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