Researchers study type D killer whales in sub-Antarctic waters for the first time.
Photo by Steve Halama (Unsplash))
by Anton Kuech
For the first time, scientists have spotted and studied a group of type D killer whales off Southern Chile. Researchers from the National Oceanic and Atmospheric Administration (NOAA) took video footage of the whales and found that their heads are more rounded and their dorsal fin is more pointed compared to other killer whales. Additionally, they appear to have a small white eye patch and are slightly smaller. Previous encounters date back to 1955, when seventeen “odd-looking whales” stranded in New Zealand. Since then, scientists have been trying to make out what relation these whales have with other killer whales and whether in fact, type D killer whales represent a new species.
"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.”
To establish the evolutionary history, scientists have collected skin samples from the whales using a crossbow with a tiny dart, which bounces off the skin of the whale, providing a harmless technique of collecting DNA from marine mammals. The genetic samples are being analysed by biologists from NOAA and are expected to reveal if in fact the type D killer whales represent a new species. Bob Pitman from NOAA stated "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.”
Scientists have previously introduced the idea of more than one species of killer whale, given strong differences in behaviour and physical variations. In the Southern Ocean, three types of killer whales have been identified: Type-A are the “typical” killer whales that live in open water and feed on big marine mammals, such as minke whales. Type B or “pack ice” killer whales are smaller in size and known for knocking seals off ice by creating large waves. The newly studied type-C are the most different looking and smallest amongst the Antarctic killer whales, found to feed predominantly on fish.
Officially, killer whales are defined as one species, Orcinus orca, but Robert Pitman pointed out “Not only are they very different-looking, but most importantly, the fishermen report that quite often, they see both types of killer whales, regular killer whales and Type Ds come into their fishing gear to take fish off. And when they do the larger regular killer whales drive off the smaller Type Ds and keep them at bay. So, this is important information that shows why Type D can manage to look different than regular killer whales because they don't socialize with them and they almost certainly don't interbreed with them.”
It remains unclear whether, in fact, type C is a new species of killer whale, however, genetic analyses are expected to help clarify the species evolutionary connections. All in all, the study on this remarkable mostly undiscovered killer whale type is an important milestone in marine mammalogy.
