An extremely rare, 10-year-old Sumatran tiger has died at Zoo Atlanta.

Officials had been monitoring the health of Emerson after the rare big cat began showing signs of lethargy and a lack of appetite.

"When he did not respond to veterinary treatment, during the evening of November 8, 2017, the veterinary team performed an emergency diagnostic exam in an effort to determine the cause of his illness, but Emerson did not survive," the zoo said in a statement.

“This is a devastating loss for the Zoo Atlanta family, not just of this magnificent individual we were only just beginning to get to know, but for the entire Sumatran tiger population,” said Dr. Jennifer Mickelberg, vice president of collections and conservation. “Tigers are now more numerous in zoos than they are in the wild, and it is critical that we preserve their populations. The loss of any individual is very difficult.”

Emerson the Sumatran tiger IMAGE ZOO ATLANTA

The tiger's death comes in the wake of recent another animal death in Atlanta, this one at the Georgia Aquarium, when a beluga whale calf died in its mother's womb.

Born November 24, 2006, at the Sacramento Zoo, Emerson was on loan to Zoo Atlanta from the Jackson Zoo in Mississippi. Zoo officials hoped Emerson would pair with Chelsea, Zoo Atlanta’s 14-year-old female tiger. He arrived in Atlanta in May 2017.

Sumatran tigers are among the most critically endangered of all the planet’s remaining tigers. Believed to number fewer than 400 in the wild on the Indonesian island of Sumatra, the species faces serious pressures from habitat loss and poaching.