Georgia Aquarium's beloved beluga whale Maris died suddenly on Oct. 22 of unknown causes. Necropsy results showed the healthy animal died of acute heart failure.

Georgia Aquarium's veterinarians and University of Georgia's pathologists conducted the joint necropsy. Georgia Aquarium posted the results which reveal microscopic lesions on the animal's heart and various tissues.

"Maris died from acute heart failure of undetermined etiology. No predisposing cause for the heart failure could be determined from the necropsy. An acute disturbance in heart function is suspected as one possible cause," said Georgia Aquarium's chief veterinary officer and senior vice president Dr. Gregory Bossart. The necropsy results also showed no evidence of any infectious illness.

Bossart shared that Maris received her weekly routine examinations prior to her death. Her last exam revealed no sign of illness. Her eating habits during the last few days of her life were also normal. She also showed normal interactions with two other beluga whales - Qinu and Grayson - living at the Georgia Aquarium. On Oct. 24, Georgia Aquarium held a press conference for the sudden loss of Maris.

"Maris was one of the first beluga whales at Georgia Aquarium and inspired millions of guests each year. The bonds that were created over the last ten years between Maris and her animal care and veterinary teams were truly special," said the Aquarium's chief executive officer and chairman Mike Leven.

Maris was born at the New York Aquarium in 1994. She was relocated to the Georgia Aquarium in Atlanta in November 20015 where she spent the last 10 years of her life.

In May 2012, Maris gave birth to a calf but died less than a week later. Earlier this year, Maris gave birth to a calf which also died after failing to gain enough weight. The calves' father was Beethoven, a male beluga whale that lived in the Georgia Aquarium with Maris. For breeding projects, Beethoven was loaned to the Shedd Aquarium in Chicago.