Subantarctic Killer Whale

## About

A Subantarctic killer whale surfacing.

The Subantarctic killer whale ***(Orcinus orca)*** formerly the type-D killer whale until 2010, is a possible separate species of orca, that is currently listed as an ecotype/variant. Unlike the standard killer whale known most commonly by the public, the type-A killer whale, Subantarctic killer whales have much different features in terms of their outward appearance. Most notably, the Subantarctic killer whales are smaller and have larger, more bulbous heads. Other than these differences the ecotype remains similar to others, with the exception of their considerably smaller, pill-shaped eyespots, their curved and pointed fins, as well as their slightly smaller size. Due to the Subantarctic killer whale's vast morphological and phylogenetical differences to type-A orcas, the ecotype is likely a new species of killer whale rather than just another regional variation however, as of currently, it has remained an ecotype. Subantarctic killer whales are similar in size to type-A killer whales however, males are larger than females. The exact measurements of the ecotype however, are unknown, due to the animal's allusivity.

## Diet

Like all killer whale ecotypes, Subantarctic killer wales are obligate carnivore. Unlike other ecotypes however, the Subantarctic variety most commonly prey on various fish species. This is odd, as the other forms all specialise in the hunting and consumption of marine mammals.

## Conservation Status

Killer whales are classed as data deficient by the IUCN, and as all ecotypes are considered to be the same species, by extension, the Subantarctic killer whale is also a data deficient ecotype. Though the threats of killer whales as a whole are known well and have been studied thoroughly, threats specific to the Subantarctic killer whale are unclear as of currently and have not been studied.

## Range and Population

As their name suggests, Subantarctic killer whales can be found in Subantarctic regions. The killer whales can most often be found offshore from the Antarctician mainland, typically preferring cooler climates however, the ecotype is suspected to avoid the coldest temperatures purposefully. Despite this, it is not uncommon for the killer whales to inhabit cool subtropical or tropical waters, such as those around Chile and New Zealand, where the animals have been documented. Unfortunately, much like many of the other features of the Subantarctic killer whale, its population is also unknown.

## Behaviour

A pod of 17 Subantarctic killer whales were first discovered in 1955, on the coast of Paraparaumu, New Zealand. It is unknown as to why the animals beached themselves during the mass stranding. Though initially thought to be genetic aberration, this theory would be discredited, after a photograph of some whales in the Southern Indian Ocean with the same eyespots was shown to lead type-D killer whale researcher Bob Pitman, in 2005. After this encounter, the Subantarctic killer whale was deemed the largest animal to be undiscovered by science for so long and likely the last large animal to ever be discovered. Though males are larger than their female counterparts, females rule the pod in a form of matriarchy. The most elderly of the female whales will lead the familial pod, with the descending generations all being members of the pod, for example, a calf will remain with its mother in the same pod for its entire life. The specific breeding habits of the Subantarctic killer whale is unknown. Killer whale ecotypes can further be categorised into three main categories, resident, transient and offshore. Resident individuals are the most well known, as they frequent the coasts of their range, remaining close to land. Transient killer whales are less common and will travel up and down the coastlines of their range, rather than having a designated territory. Offshore killer whales are the most seldom seen as they occur far at sea. Subantarctic killer whales fit into the offshore category and so they are incredibly hard to study. Typically it is safer, more efficient and more cost effective for marine biologists to examine resident individuals, rather than offshore individuals and these factors have only contributed to how little information we currently have on the nature of the Subantarctic killer whale.

### Relationship with Humans

Due to how uncommon they are, Subantarctic killer whales do not really ever interact with humans. Specific expeditions to explore the lives of Subantarctic killer whales have not really brought new information to the scientific community and the ecotype remains extremely elusive. It is likely however, that humans interact with Subantarctic killer whales unintentionally, through tourism in Antarctica. Vessels operated in these waters can inhibit the Subantarctic killer whale's echolocation and hearing efficiency which may cause major effects however, tourism is heavily monitored in Antarctic waters. Through an encounter by fishers in Cape Horn, Chile, it can be inferred that the Subantarctic killer whale is far less excitable around humans compared to type-A killer whales, as they stayed far away from fishing boats, while the type-A individuals stole from the fishermen's catches. Though this behaviour may not be the norm, as a pod of 30 Subantarctic killer whales regularly examined the research boat, the Australis, which was in the same region after the sighting.

## In Captivity

No Subantarctic killer whales exist in captivity and with the rising concerns of Cetacean welfare in zoos (specifically killer whales), they will likely never be found in captivity.

## Sources

* Scientists Find Mystery Killer Whales off Cape Horn, Chile | NOAA - https://www.fisheries.noaa.gov/feature-story/scientists-find-mystery-killer-whales-cape-horn-chile
* Type-D Killer Whale: How Did the Largest Unknown Species Stay Hidden | Ocean Syrup - https://oceansyrup.com/type-d-killer-whale/
* Type-D Orcas: Mysterious Stalkers of the Southern Oceans | Orcazine - http://orcazine.com/type-d/
* Drama in the Plural - Mass Strandings | Orcazine - http://orcazine.com/orcas-and-mass-strandings/