Ralph, the popular whale shark at the Georgia Aquarium, has died. Ralph was one of only four whale sharks in the aquarium.

His keepers say he was only a teenager and they are unsure about what caused his death. They say shortly before his death, Ralph had not been eating well and had been showing some unusual swimming patterns. He had been at the aquarium since 2005.

The aquarium's other three whale sharks are Norton, Alice and Trixie. The aquarium's other famous resident, Gasper, a beluga whale, was euthanized a little more than a week ago after suffering from poor health.

The Georiga Aquarium is said to be the world's largest. It houses more than 100,000 specimens.