Beluga whales demonstrate mirror self-recognition in landmark 2001 study

In early 2001, a team led by Diana Reiss installed a two-way plexiglass mirror in the shared pool of four female beluga whales at the New York Aquarium, part of the Wildlife Conservation Society, and observed them across 98 sessions. The adult whales Kathy, Marina, Natasha, and Natasha’s daughter Maris were also shown a transparent control surface. Natasha, 21, and her 7-year-old daughter Maris exhibited extensive self-directed actions, including bubble blowing and barrel-rolling while watching their reflections, and lingered longer at the mirror than at the control.

Trainers later placed a non-toxic mark on parts of their bodies that could only be seen via one outlet; Natasha repeatedly examined the mark, satisfying the “mark-directed” component of one outlet test, while Maris did not pass the mark trials but still showed suggestive self-recognition behaviors. The study, titled “Evidence for mirror self-recognition in beluga whales (Delphinapterus leucas),” appeared in PLOS ONE in May 2026, marking the first evidence of this ability in a non-delphinid cetacean. The results imply that belugas possess a level of self-awareness linked to complex social cognition, expanding the known range of species capable of mirror self-recognition.