SHIMODA, Shizuoka -- A bottlenose dolphin named Nana marked her 15,666th day at the Shimoda Aquarium here on Oct. 4, the longest a dolphin has ever been held at a Japanese aquarium.

In a ceremony held at the aquarium that floats on a cove, Shimoda Mayor Yusuke Fukui presented Nana with a special citizen's award and resident certificate for her contribution to promoting local tourism over her 43 years at the aquarium.

Though Nana tends to be moody and often no longer participates in aquarium performances, on this day she watched from nearby as a fellow dolphin broke a decorative paper ball in celebration.

"I wonder if Nana understood she was the center of the show today," an aquarium employee said.