The female Coquerel's sifaka died from Addison's disease.

The Maryland Zoo is mourning the death of a treasured lemur. Anastasia, a critically endangered Coquerel's sifaka, died on August 12 from complications related to Addison's disease. She was 17 years old.

Addison's disease is an affliction that targets the kidneys and their ability to produce necessary hormones like adrenaline which helps various bodily functions. While she initially responded well to treatment, her older age ultimately made recovery impossible. Addison's is not typically found in her species, the zoo said.

Also called "Ana," the zoo staff remembered her headstrong personality, which is a common trait among female sifakas.

“Ana ruled the roost, so to speak," Erin Grimm, mammal collection and conservation manager said in an official statement: "She was usually first to eat, selecting her favorite foods and was adept at breaking up family squabbles. She was also gentle, yet fiercely protective of her offspring. Her death is quite a loss for all of us.”

If you're familiar with the kid's show Zoboomafoo, then you've definitely seen the Coquerel's sifaka. Native to the forests of Madagascar, they have white and brown coats with striking yellow eyes. They're notably one of the few lemurs who can hop on their hind legs–the Duke Lemur Center notes they can reach up to 20 feet within a single jump through the trees or ground. Their typical lifespan is 18-20 years and they are considered a critically endangered species by the International Union for Conservation of Nature.

Ana arrived at the zoo back in 2009, where she was paired with male sifaka, Gratian. They produced five offspring together during their partnership. Due to her passing, Gratian will be relocated to a different accredited zoo to be paired with a new breeding partner. The zoo, which counts among the 13 zoos housing the primates, hopes to eventually bring another Coquerel's sifaka into the fold.

"Sifaka are an endangered species and we are honored to participate in this important program helping to conserve these amazing animals," Grimm said. 

We're sad to see such an amazing animal go. Rest in peace, Anastasia. You will be missed.

Do you have any memories of Anastasia the lemur? Please send your thoughts to the Maryland Zoo in the comments.