Antarctic Type A Killer Whales

***This article contains imagery of deceased animals. Viewer discretion is advised.***

## Antarctic Type A Killer Whales

A mature female Antarctic Type A killer whale surfacing in the Gerlache Strait. Photo provided by Jim Wilson, February 26th, 2015

### Typical Diet

*Marine Mammals** Minke Whales
* Elephant Seals
* Arnoux's Beaked Whales

*Cephalopods*

* Squid

*Fish*

### Hunting Behavior

They chase the prey silently, and then pursue it on each side flank, then they begin to batter and bite it, and when the prey is tired, they drown it.

### Common Features

* Medium-sized, parallel to the body axis eyepatches
* Closed or open saddle-patches
* Large size, up to 9m (30ft)

### Distribution

Antarctica *(Austral Summer)*, South America

Antarctic type A killer whales, also known as Antarctic killer whales or simply Type A killer whales are a large mammal-eating killer whale ecotype, they're known to be the largest killer whale ecotype in the world, reaching to a maximum size of 9m (30ft). They mainly occur in offshore ice-free waters of Antarctica during the austral summer, having a circumpolar distribution; preys mainly upon Antarctic Minke Whales *(Balaenoptera bonaerensis)* and other marine mammals.

## Social Structure and Population Status

Antarctic killer whale pods often consist of 10 to 15 animals. Photographic analysis estimated a high average annual survival, and an abundance that increased in a 95% from a low of 91 killer whales in 2009/2010 to a high of 149 in 2016/2017.

## Common Physical Features

### Morphology

Type A killer whales have a typical black and white color pattern. Eyepatch is medium-sized and it's oriented parallel to the body axis. Saddle patch is often bright and wide, it extends to the midline of the dorsal fin; and can be open (opened in ''hook'' or in ''notch'') or closed (both in ''bump'' or ''smooth'') and it lacks a dorsal cape. Both males and females' dorsal fin is pointy, wide and triangular shaped.

### Size

Males reach an average size of 7.3m (23.9ft) to 7.8m (25.5ft), maximum sizes ever recorded were from 8.9m (29.1ft) to 9m (30ft). Females reach in average 6.4m (20.9ft) maximum size ever recorded is 7.7m (25.2ft).

## Diet

Antarctic (Type A) killer whales' diet consists mainly of Antarctic Minke whales *(Balaenoptera bonaerensis)**,*** but also can take on Southern Elephant Seals *(Mirounga Leonina)*, and Arnoux Beaked Whales *(Berardius arnuxii)*.

The main prey items found in the stomach of 785 Antarctic (type A) killer whales captured by the Soviet fleets: 89.7% marine mammals, 7.1% squid and 3.2% fish. A potential implication of dietary specialisation (and perhaps size disparity) is an incidence of ‘cannibalism’ in southern hemisphere killer whales, reported by Shevchenko (1975) that may have been a case of a larger, mammal-eating form (possibly type A or B1) preying upon a smaller form (B2 or C). Reports mention that they have been sighted chasing, but not catching penguins.

## Two Antarctic killer whales

* Warning
* \*Graphic Content\*

### Image Credit

Mikhalev, Y. A. (2016). Killer whales of Antarctica: distribution and some aspects of biology. Ukrainian Antarctic Journal, (15), 122-130. (In Russian)

## Physical Traits

### Ecotype

Antarctic type A

During 1954 to 1978 - 1979 (sixteen seasons), in the Southern Hemisphere, Soviet whaling fleets captured 738 killer whales. The average catch per season was only 29 - 30 killer whales. At the same time, in three trips, no killer whales were captured, and on two trips, only one. The largest production occurred in the 1958-1959 flight. 110 killer whales. With such a small catch, naturally. In fact, there were barely any few opportunities to study the species. Some information about Antarctic killer whales reported in the works of several scientists. The material for this study was the results of the slaughter of killer whales by the Odessa “Slava” and “Soviet Ukraine” whaling fleets in the periods of 1960's to late 1970's, as well as observation records of the occurrence of killer whales from ships, research whalers from these fleets. Statistics from the International Whaling Commission (IWC) were also used.

During the period of studies, the Odessa fleets captured 323 killer whales: 205 males and 118 females. The sizes of the males ranged from 4.5m to 9.0m, the average length was 7.26m. The sizes of captured females ranged from 3.7m to 7.7m, with an average length of 6.42m. Observers on research whaling ships recorded at least 480 pods (groups) of killer whales. The number of killer whales in pods varied from 2 or 3 to 30 individuals. Sometimes killer whales banded together in pods of about 40 to 50, or even 100 to 200 or even more animals. However, groups of 5 to 15 individuals were sighted more frequently. They typically accounted for up to 35-40% of all sightings.

## Distribution

Antarctic type A killer whales travel to Antarctica during the Austral Summer, and it migrates to lower latitudes during the winter. During the austral summer, type A's ranged widely on the continental shelf in the austral summer in the Western Antarctic Peninsula; but also traveled over long distances into the Southern Ocean and beyond off both sides of South America (up to Northen Chile, Uruguay and Brazil). Antarctic killer whales dive depths are less than 50m (164ft) below the surface.

## References

1. ↑ 1.0 1.1 1.2 1.3 Abundance of Type A killer whales (Orcinus orca) in the coastal waters off the western Antarctic Peninsula. Holly Fearnbach · John W. Durban · David K. Ellifrit · Robert L. Pitman
2. ↑ 2.0 2.1 Pitman, Robert & Ensor, Paul. (2003). Three forms of killer whales (Orcinus orca) in Antarctica. J Cetacean Res Manage. 5.
3. ↑ Durban, JW & Fearnbach, Holly & Paredes, A & Hickmott, Leigh & LeRoi, DJ. (2021). Size and body condition of sympatric killer whale ecotypes around the Antarctic Peninsula. Marine Ecology Progress Series. 677. 10.3354/meps13866.
4. ↑ 4.0 4.1 Mikhalev, Y. A. (2016). Killer whales of Antarctica: distribution and some aspects of biology. *Ukrainian Antarctic Journal*, (15), 122-130. (In Russian)
5. ↑ Pitman, Robert & Durban, John. (2010). Killer whale predation on penguins in Antarctica. Polar Biology. 33. 1589-1594. 10.1007/s00300-010-0853-5.
6. ↑ Pitman, RL, Durban, JW, Joyce, T, Fearnbach, H, Panigada, S, Lauriano, G. Skin in the game: Epidermal molt as a driver of long-distance migration in whales. *Mar Mam Sci*. 2020; 36: 565–594. https://doi.org/10.1111/mms.12661