Lulu, a 46-year-old female western lowland gorilla, died Monday at the Columbus Zoo and Aquarium after suffering a pair of seizures.

Lulu was taken to the hospital on Saturday to have the seizure controlled with medication, said Dusty Lombardi, animal care and conservation vice president. On Sunday, Lulu had what Lombardi described as “a perfect day.” On Monday, Lulu began to have another seizure, and died.

The zoo will perform a necropsy, or animal autopsy, to determine the exact cause of death.

“It’s a tremendous loss for us. Lulu was part of the surrogate program, which means she adopted babies and raised them, and she was a vital part of the group she was in,” Lombardi said. “It’s a big loss not only for the Columbus Zoo, but the gorilla community as well.”

Lombardi said older gorillas like Lulu are important to the gorilla community because they impart knowledge to younger gorillas. The life expectancy of male gorillas is about 25-35 years, and the life expectancy of a female gorilla, like Lulu, is generally 35-40 years.

Lulu was a wild-born gorilla brought to the Central Park Zoo in 1966, when she was estimated to be 2 years old. She has lived in the Columbus Zoo since she moved there in 1984. Lulu was one of 17 gorillas in the collection at the Columbus Zoo.

“Lulu was a favorite of zoo staff and visitors,” said Dale Schmidt, president and CEO of the Columbus Zoo, in a press release Tuesday. “Easily recognizable by her pink tongue that was perpetually sticking out; she could be found surrounded by her gorilla family which always included youngsters.”

Lombardi said the Columbus Zoo was thankful Lulu was around for as long as she was.

“Lulu was really special to us,” Lombardi said. “She was a very happy, very loving animal.”