A beluga whale at the Georgia Aquarium in Atlanta has died, the aquarium said.
The 21-year-old whale, Maris, has lived at the aquarium for nearly 10 years. Aquarium officials said Maris was eating normally in the days before its sudden demise Thursday afternoon.
"This is a case of sudden, acute animal death," Dr. Gregory Bossart, the aquarium's senior vice president and chief veterinary officer, said in a statement. He said an exam earlier this week showed no signs of illness.
A necropsy was conducted, but aquarium officials said the cause of the death may never be known.
"Maris was one of the first beluga whales at Georgia Aquarium and inspired millions of guests each year,” Mike Leven, the aquarium’s executive director and CEO, said in a statement.
"The bonds that were created over the last ten years between Maris and her animal care and veterinary teams were truly special. This unexpected loss is difficult," Leven said.
Maris was born in 1994 at the New York Aquarium and was sent to Georgia in November of 2005, the aquarium said.
Maris gave birth to two calves during her time at the Georgia Aquarium, in 2012 and in May of this year, NBC affiliate WXIA reported. Neither calf survived.
The Georgia Aquarium has two other beluga whales, Grayson and Qinu.
Beluga whales have a lifespan of between 35 to 50 years, according to the National Oceanic and Atmospheric Administration.