The world's oldest known killer whale, affectionately known as Granny, is missing and presumed dead, researchers say. Estimated to be over 100 years old, the matriarch's official name was J2.
She was the focal point of a recent BBC documentary that followed biologists' study of her clan of orcas, an effort to unravel an evolutionary mystery.
Studying female orcas, which live long beyond their reproductive years, has revealed insights into the menopause.
Only three mammals are known to experience menopause - orcas, short-finned pilot whales, and humans.Even our closest ape cousins, chimpanzees, do not go through it. Their fertility peters out with age and, in the wild, they seldom live beyond childbearing years.
Following Granny and other matriarch, killer whales have shown their crucial role within the family group. They guide the pod as it forages, take care of other females' young calves and even feed the larger males.
These post-reproductive female leaders help their families to survive, and the advantage they offer could show what drives a species to evolve to stop reproducing.