World's oldest bottlenose dolphin Still missing

Flashback: Before her disappearance, Nicklo was an active member of the Sarasota Bay dolphin community, which includes about 170 dolphins between the southern end of Tampa Bay and Venice.

• Researchers from the Chicago Zoological Society's Sarasota Dolphin Research Program have been studying local dolphins for 50 years and named Nicklo years ago.
• They pulled a tooth in 1984 to determine her age.

What happened: No one is sure, but since dolphins tend to stay in the same area for life, Nicklo is presumed dead. She was last spotted in 2017.

• Researcher Dr. Randy Wells tells Axios that Sarasota Bay's next-oldest dolphin is in its 50s. There could be unobserved dolphins older than Nicklo out there, but no one has recorded them.