Meet the Southern Orcas
- Elding's research team
- 1 day ago
- 4 min read
Welcome to the latest edition of our Orca blog. As promised, here is the second part about the different ecotypes. This time we look at the orcas in the Southern Hemisphere.
In our recent blog we started with the smallest of orcas, this time we will start with the biggest!
Type A: Antarctic Orcas
These large orcas grow up to 9.5m! They prefer the open areas of the Southern Ocean, which makes them hard to study, therefore not a lot is known about them. Primarily, they hunt minke whales, following their migration in and out of Antarctic waters, but also elephant seals or squid. It is thought, these are the same orcas that beach themselves in Argentina to hunt for seals. During the austral summer, type A's range widely on the continental shelf in the Western Antarctic Peninsula; but also travel over long distances into the Southern Ocean and beyond off both sides of South America (up to Northern Chile, Uruguay and Brazil). Their pods consist of 10-15 individuals.
Type B1 (large): Pack Ice Orcas
They forage on (Weddell) seals in the loose pack ice around the Antarctic continent. Famous for their cooperative wave-washing hunting technique, the Pack Ice Orca has another striking feature, which it shares with the smaller Type B2. They have a brown or yellowish coloration due to diatoms (a form of algae) on their skin. This covers the light grey colour like a veil. They have a cape of paler coloring from their forehead to just behind the dorsal fin. The Type B1 orcas are abundant between Adelaide Island and the mainland Antarctic peninsula but they migrate to lower latitudes in a short amount of time, in order to shed their diatom-covered skin that accumulated in Antarctic waters. There are around 102 individuals, but unfortunately with a declining trend. Their pod size is about 5-14 orcas. Maximum length is around 8.0m and they have the biggest eyepatch of all killer whales.
Type B2 (small): Gerlache Orcas
Gerlache orcas are named after the Gerlache Strait of the Antarctic Peninsula where they are most often found, but they were also tracked passing through the Scotia Sea, east of the Falkland Islands, and northward off the eastern coast of South America. They may appear brown or yellowish, like the Type B1 orcas, due to diatoms but they have a cape of paler color, as well as the larger eye patch. Short trips to lower latitudes, in order to shed their diatom-covered skin, like the bigger Type B1’s, are common. The composition of their diet is unknown, but they have been seen feeding on penguins and are usually spotted around penguin colonies. These Type B2 killer whales travel in pods between 36 and 75 individuals. They reach an average size of 6.4m but the maximum size is unknown.
Type C: Ross Sea Orcas
The smallest ecotype is the Ross Sea orca – they reach 6.0m. Like other Antarctic orcas, they are grey and white and have a diatom coating that gives them a yellowish shade. The cape of Ross Sea orcas is darker than the rest of their body, and they have a very distinctive and forward slanted eye patch. Typically seen off Eastern Antarctica in thick pack ice, Ross Sea orcas have been seen eating Antarctic toothfish and Antarctic cod. It is still unknown if they specialize solely on fish. The vocal behaviour of this ecotype has been shown to consist of a high number of different call types, and they are vocal whilst hunting.
Type D: Subantarctic Orcas
Subantarctic orcas were first discovered in 1955 due to a mass stranding event in New Zealand. At the time, they were thought to be a mutated type of the orca ecotypes. While they share the black-and-white colouring and saddle patch patterns of other orcas, these orcas have shorter dorsal fins, rounder heads, and the smallest eye patches of any ecotype, giving them a very specific appearance. Since then, there have only been a handful of sightings of this rare ecotype, but enough for researchers to realize they are a unique ecotype and not just a mutation. But sub-Antarctic killer whales show poor genetic diversity, as genomes show among the highest level of inbreeding reported for any mammalian species. The first video record of this type was taken in 2014 between the Kerguelen and Crozet Islands and again in 2017 off the coast of Cape Horn, Chile. Its geographic range appears to be circumpolar in sub-Antarctic waters between latitudes 40°S and 60°S. They have been seen consuming Patagonian toothfish off the hooks of fishermen, but like the Ross Sea orcas, it is still unknown if they are fish specialists. The maximum size for females is 5m and the group size of these killer whales is relatively large, having between 10 - 35 individuals.
And that’s a wrap! Thank you for staying tuned and reading along, hopefully you enjoyed the ecotypes specials. Of course, we have something interesting for you in store for the next blog, so don’t miss it!
Kylie Veal
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