Luke was humanely euthanized at 35 years old after struggling from health issues.

Sad news, animal lovers: the Smithsonian National Zoo is grieving the death of their harbor seal, Luke. The zoo had him humanely euthanized on Thursday, January 23, following a chronic ear infection and high ocular pressure. At the age of 35, he was one of the zoo's oldest residents and an impressive example for his species. Harbor seals typically live until the age of 25-30, depending on their habitat.

Zookeepers noticed his withdrawal from usual behaviors like eating and socializing with the other seals in the exhibit, including 13-year-old Rabbit, as well as general disorientation in his surroundings. Veterinarians carried out treatments for his ear infection and ocular pain, such as antibiotics and eye drops, but his condition continued to suffer. After assessing the decline of his health, the zoo made the call to have him euthanized.

Since 2011, Luke had been a beloved mainstay at The National Zoo. He was transferred to the D.C. institution from Brooklyn's New York Aquarium, where he was born on June 17, 1984. American Trail keepers recalled his curious nature and easygoing temperament, a trait that made him a huge asset for helping fellow team members train other seals.

Currently, the American Trail exhibit houses gray seals Gunther, Kara, Kjya, and Birdie, and male harbor seal Rabbit. You can read the zoo's full statement here.

Do you have fond memories of Luke the seal? Share them with us in the comments.