Jack Hannah, a famous animal and wildlife expert, has reportedly decided to retire from his public life after being diagnosed with dementia.

Hannah's family announced on Wednesday that he is retiring from public life.

"Doctors have diagnosed our dad, Jack Hanna, with dementia, now believed to be Alzheimer's disease," Hanna's family wrote in a statement posted to his verified Twitter account.

"His condition has progressed much faster in the last few months than any of us could have anticipated," the statement read. "Sadly, Dad is no longer able to participate in public life as he used to, where people all over the world watched, learned, and laughed alongside him."

Jack Hannah, also known as "Jungle Jack Hannah", became famous after his several late-night TV appearances like the David Letterman Show and the Tonight Show Starring Johnny Carson. 

Those late-night TV appearances eventually landed him his own shows, including" Animal Adventures," "Into the Wild" and "Wild Countdown."

Jack, 76, has reportedly retired  from serving as director and then director emeritus of the Columbus Zoo and Aquarium in December 2020 after 42 years.

"The Columbus Zoo and Aquarium has been a major part of our lives since we moved to Central Ohio as young girls in 1978," his daughters wrote in their statement. "From day one, Dad advocated for improved wildlife habitats and focused on connecting the community with animals. After he left his active management role as Executive Director in 1992, he continued to be a spokesperson for the zoo until his retirement last year."