A type C killer whale mother and an adult individual with what appears to be twin calves swimming in Ross Sea pack ice. Multiple births among cetaceans is extremely rare. This is the only documented sighting of twin killer whales (though vanaqua.org mentions a case of twins in B.C., in which the calves’ fates are unknown)! It may seem like these orcas are caught by the ice and are forced to share this opening to breathe, but I doubt that because Antarctic killer whales are well adapted to their icy, frozen environment. #AntarcticOrcas
Type A looks like a “typical” killer whale, a large, black and white form with a medium-sized white eye patch, living in open water and feeding mostly on minke whales. Type B is smaller than type A. It has a large white eye patch. Most of the dark parts of its body are medium gray instead of black, although it has a dark gray patch called a “dorsal cape” stretching back from its forehead to just behind its dorsal fin. The white areas are stained slightly yellow. It feeds mostly on seals. Type C is the smallest type and lives in larger groups than the others. Its eye patch is distinctively slanted forwards, rather than parallel to the body axis. Like type B, it is primarily white and medium gray, with a dark gray dorsal cape and yellow-tinged patches. Its only observed prey is the Antarctic cod. Type D was identified based on photographs of a 1955 mass stranding in New Zealand and six at-sea sightings since 2004. It is immediately recognizable by its extremely small white eye patch, shorter than usual dorsal fin, and bulbous head (similar to a pilot whale). Its geographic range appears to be circumglobal in subantarctic waters between latitudes 40°S and 60°S. And although nothing is known about the type D diet, it is suspected to include fish because groups have been photographed around longline vessels where they reportedly prey on Patagonian toothfish (Dissostichus eleginoides). Types B and C live close to the ice pack, and diatoms in these waters may be responsible for the yellowish coloring of both types. Mitochondrial DNA sequences support the theory that these are recently diverged separate species. More recently, complete mitochondrial sequencing indicates the two Antarctic groups that eat seals and fish should be recognized as distinct species, as should the North Pacific transients, leaving the others as subspecies pending additional data. Source
The A, B, C, D Orcas are typically used when classifying Antarctic Killer Whales. In the rest of the world, all Orcas look like type A’s.