The killer whale, or orca, is a predatory cetacean typically found in cold ocean waters. With its easily recognizable black body and distinct white patches over the eyes and around the belly, the orca is a top (apex) predator in the marine ecosystem, with no natural enemies other than humans. Most cetacean experts consider this creature to constitute one species, named Orcinus orca, although there are a number of distinguishable ecotypes (that is, subunits or races of species that are restricted to a particular habitat); most notable are types A, B, and C (which are differentiated by size or certain body features). So far, though, scientists have not determined if these types are actually distinct species, or even subspecies, and most researchers are not inclined to reclassify the group as a whole. However, there is an elusive and rarer set of orcas, termed type D or subantarctic killer whales, which might prove to be an unequivocal new species. See also: Cetacea; Ecosystem; Killer whale; Mammalia; Marine ecology; Predator-prey interactions; Speciation; Species concept
Type D orcas inhabit the ocean near Antarctica, including the coastal waters off Cape Horn at the bottom tip of South America, where fisherfolk have occasionally described these unique marine mammals. As ocean waters in this location are rough and weather conditions are inhospitable and harsh, it is an area that has not been conducive to scientific research. Thus, type D orcas were, until now, evasive to scientists, and the animals have been difficult to track down. Originally reported in 1955, when a dozen unusual-looking orcas were stranded on a beach in New Zealand, the killer whales belonging to this type of group were photographed only once in the wild by a scientific expedition in 2005 (which was undertaking research in an unrelated endeavor). Recently, though, a team of marine specialists from the National Oceanic and Atmospheric Administration (NOAA) successfully and purposefully encountered these marine mammals in the wild. Moreover, this team filmed and photographed these orcas and was able to take tissue samples (pieces of skin and blubber) from three animals. These samples will be analyzed with regard to their genetic content. In particular, analyses of the DNA content of these tissue samples should help provide the necessary information to determine whether an assignment of a new species is warranted. See also: Antarctic Ocean; Antarctica; Deoxyribonucleic acid (DNA); Genetics
Type D killer whales differ in appearance from other killer whales. Specifically, they possess a more rounded head, a blunter nose, and a much pointier dorsal fin (which is also narrower). Moreover, they are shorter in length and smaller in size, and they have tiny white patches near their eyes, which is unusual because other killer whales have much larger and more distinctive eye patches. Also, based upon the information gathered from local fisherfolk and from marine scientists who inadvertently and briefly came across these animals while pursuing other research work, the type D orcas seem to inhabit the slightly warmer waters of the subantarctic ocean region (as opposed to colder waters closer to Antarctica), and they seem to favor fish as prey (as opposed to preying on marine mammals, such as seals). With this provisional knowledge, which should be aided by the results of the forthcoming DNA analyses, scientists are better positioned to accept the possibility of the identification of a new species of orca. See also: Population ecology; Population genetics; Trophic ecology
