A strange and rare group of orcas has been stranded on a beach in Chile – the first such occurrence in 67 years and only the second ever.
orcas (Orcinus orca) They belong to the ‘Type D’ subgroup – a distinct group of orcas native to the Southern Hemisphere. Type D orcas are so different from other orcas that some scientists suggest they may actually be a separate species entirely.
“I think there is a good possibility here that this Type D killer whale is one of the largest undescribed species remaining on the planet,” Robert BatemanA marine ecologist at Oregon State University told Live Science.
Orcas divided at least Nine different subgroupsor “types” scattered all over the world. But the Type D Orcas—which have white spots smaller than their eyes and round “melon” heads—are some of the most recognizable.
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Scientists first discovered D orcas in 1955 when a group of unusually shaped killer whales washed up on a beach in New Zealand. But the animals have not been identified as a distinct group of orcas Until the early 2000s, When researchers spotted whales whose odd facial markings and body shapes matched 1955 New Zealand orcas in images from across the Southern Oceans.
Beaching in 1955 was the only known stranding of Type D orcas until the last two incidents. In November last year, researchers in Punta Arenas (at the southernmost tip of Chile) were notified of a stranded female, which they identified as a Type D Orca because of its distinctive small eye patch, rounded head and curved dorsal fin. The team took pictures and measurements of the animal and transferred its remains to a museum.
Later that month, a group of eight orcas were reported stranded about 2.5 miles (4 kilometers) away. These individuals were more promiscuous, but the researchers believe they were also Type D Orcas. Researchers published Results From their study published June 8 in the journal Polar Biology.
Scientists aren’t sure why the nine orcas died or ended up on the beach. Whales may cut themselves for it a variety of reasons, including disease or human use of underwater sonar, although the causes are not fully understood. The team’s analysis of the lone female orca showed that she was a healthy adult. There were no signs of human involvement in the death, such as entanglement or a collision with a boat. Scientists did not detect the presence of parasites in the animal, and all the abdominal organs and heart appeared healthy. The other eight, most decomposed from orcas, were measured, but no autopsies were performed on them.
Type D orca filaments are likely rare, Pittman said, with good reason. D orcas only live between 40 and 60 degrees south latitude, and there is very little land on which they can beach in this stretch of ocean—the only major land masses being New Zealand, Tasmania, and the lower tip of South America.
“I have to admit, I never thought I would hear about another Type D killer whale stranding in my life,” Bateman, who reviewed the new paper before it went to print, told Live Science via email.
Other orcas are found as far south as Antarctica and as far north as Greenland. The ranges of some of these species overlap—but they are They don’t seem to be matingor even necessarily interact with each other.
Scientists have speculated such type D orcas other groups They may be different enough from each other to qualify as separate species or subspecies.
Did Bateman et al Some of the first genetic analyses type D Orcas and found that the group probably had a very small population with a high degree of inbreeding.
Bateman said unraveling the mystery of how these enigmatic marine mammals relate to other orcas probably requires more biopsies and tissue samples to learn more about the biology of the D-type orca.
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