Scientists from the National Oceanic and Atmospheric Administration announced via a press release on March 7 they had collected the tissue samples necessary to determine whether a form of orca called the type D killer whale, observed off the southern tip of South America, is a distinct and unique species. According to NOAA's Michael Milstein, this is the first time scientists have seen these animals live. "We are very excited about the genetic analyses to come. Type D killer whales could be the largest undescribed animal left on the planet and a clear indication of how little we know about life in our oceans," Pitman said in an early press release.
The research team set out looking for type D whales in January aboard the research vessel Australis. Despite eight days of rough seas and no sightings, Pitman said the group was in relatively good spirits: "We had six scientists on board—my wife and I, and three other killer whale scientists that I have previously spent quite a bit of time with in the field. The only new person was a whale scientist from Argentina, Mariano Sironi, who was great to work with. We are all talking about doing this again next year if the opportunity arises."
The Australis was returning to Cape Horn when a group of 25 or 30 type D killer whales approached the boat and remained nearby for about three hours. According to the researchers, the whales seemed curious and interacted with a hydrophone that had been released overboard to record their vocalizations. The research team took photographs and video and collected three tissue samples from a few individuals using crossbow darts. Pitman described the tool as "a low-power, recurved crossbow available from sporting-goods stores" that teams like his have been using for decades. The crossbow dart bounces off the animal, collecting a portion of blubber and other tissue "about the size of a pencil eraser." The dart floats, and the team collects it later.
"All killer whales studied to date occur in pods made up of a matriarch, her offspring, and her daughters' offspring—males breed outside of the group," says Pitman. "We don't know anything about the social structure of type D killer whales, but we didn't see anything to suggest that they are doing anything different."
Pending permission from the Chilean government to remove the samples from the country, they plan to run them through genetic tests to see if the whales are truly different enough from other orcas to constitute a unique species, with results expected in a few months.
Type D killer whales were first described in 1955, when a few stranded individuals were observed in Paraparaumu, New Zealand. The specimens had rounder heads and thinner dorsal fins than other orcas and small white patches around their eyes instead of big ones. Years later, French scientist Paul Tixier observed the same small eyepatch in photographs taken by fishermen in the Indian Ocean. In more recent times, tourists in Antarctica have also taken photographs of marine wildlife, and they captured images of the white-patched orcas on six separate occasions. But professional scientists had never viewed living type D whales until Pitman's expedition this month.
"By collecting the first biopsy samples ever obtained on this form of killer whale, Pitman's expedition [promises to] increase our knowledge on genetics, evolution, feeding preferences, and resource partitioning in type Ds, and in killer whales as a whole," Tixier commented on the January sampling in National Geographic. "We obtained three samples—this should give a strong sense of how different type D is from other killer whales. And I suspect that we might be looking at species-level differences," says Pitman.
In 2010, Pitman, Tixier, and other colleagues co-authored a paper describing these whales and suggesting the common name "subantarctic killer whale" for their tendency to prefer the 40- and 50-range latitudes to colder ones. When asked, Pitman would say of the name, "Laypeople tend to prefer the name orca; most of us who work with this animal find the name killer whale to be apt.".