The world's oldest known killer whale is presumed dead

The world's oldest known killer whale is missing and is feared to be dead.

The female orca is officially known as J2, but more affectionately called Granny. According to BBC, Granny is estimated to be older than 100 years old.

The mammal was the star of a BBC documentary that followed her clan of orcas and explored the topic of menopause.

Orcas, short finned pilot whales and humans are the only three known mammals to experience menopause.

The research conducted in the documentary played a crucial role in understanding the family role that matriarch orcas play in a clan.

Lead evolutionary biology researcher professor Darren Croft of the University of Exeter said of the news, "it was inevitable that this day was going to come but it is very sad news and a further blow to this population."

The Center for Whale Research, which has been studying Granny for forty years, first reported her death on their website.

Croft added "although J2 is gone we will continue to benefit, for many decades to come, from the incredible data collected on her life over the last 40 years by the Center for Whale Research."