Belugas join a rare animal kingdom club—they can recognize themselves in a mirror

Beluga whales have some of the most iconic faces in the sea, with their marshmallow noggins and upturned mouths—and a new paper reveals they’re more self-aware than previously known. 

A study published today in PLOS One shows that belugas are able to recognize themselves in mirrors, using the tools to peer at themselves, watch themselves do barrel rolls, and examine their own mouths. 

The whales join a small but growing group of animals, including great apes, magpies, and cleaner wrasse fish, who share "this capacity we thought was uniquely human," says Diana Reiss, a marine mammal scientist and cognitive psychologist at Hunter College, City University of New York and one of the paper's authors. "We have this list of the things that only humans do, and over time we've been checking [them] off…showing other animals can do them as well."

An unexpected reunion

Chimpanzees were the first animals to demonstrate mirror self-recognition in a 1970 study. Inspired by this work, Reiss began investigating the trait in bottlenose dolphins and Asian elephants—two other animals with “large, complex brains,” she says—and found that they also passed the test. To date, bonobos, orangutans, gorillas, magpies, and cleaner wrasse fish are among the animals who have demonstrated the ability. 

In general, species who show mirror self-recognition tend to be highly social and empathetic, Reiss says. Humans start demonstrating mirror self-recognition when they’re about 18 months old, as their sense of self-awareness begins to develop. Bottlenose dolphins, as Reiss discovered, grow up faster and can recognize themselves in mirrors at a much younger age than humans.

In 2001, Reiss decided to test another big-brained, social species: beluga whales. She and a former student worked with four captive belugas at the New York Aquarium of the Wildlife Conservation Society: three adult females named Kathy, Marina, and Natasha, and Natasha's 7-year-old daughter, Maris. The researchers affixed a mirror to a window in the belugas' shared pools for two hours at a time and filmed how they responded. As a control, they also filmed the whales' responses to transparent plexiglass put up in the same place.

But life got busy. Reiss published her findings on dolphins and elephants, but time constraints prevented her from analyzing the beluga footage in detail. "We kind of let it go," she says. 

Then, in 2020—nearly twenty years later—Alexander Mildener enrolled in Hunter College's animal behavior and conservation program, where Reiss teaches. Mildener had grown up visiting these exact belugas at the New York Aquarium, an experience that left him "completely transfixed" as a child and eventually led him to pursue a career in marine conservation science, he says. 

During the Covid-19 pandemic, which limited field research opportunities, Mildener needed a thesis project. So, Reiss dug up the beluga mirror tapes for him to digitize and analyze. Mildener, the new paper's lead author, spent lockdown carefully watching videos of his old friends the belugas, "the very whales that inspired me to be in this field in the first place," he says.

Pec shimmies and bubble bites

Animals who end up demonstrating mirror self-recognition usually go through a particular journey of understanding. First, there's "a reaction to the mirror itself," Reiss says. Dolphins often try to look behind it, while an elephant might give it a tap with its trunk. 

Next, they start behaving more socially, as though the mirror is showing them a peer. For animals who go on to recognize themselves, this stage is quickly supplanted by what researchers call "contingency testing"—repetitive behaviors that seem designed to check whether the image is responding to them. Reiss compares this to how humans interact with security cameras in places like drugstores: When you think you see yourself on the monitor, she says, "you might move your head or raise your hand—'Is that me?'"

For self-recognizing animals, "that seems to be where the light bulb goes on," she notes. After that, they begin using the mirror as a tool to view themselves, exhibiting what's known as "self-directed behavior."

As he watched the beluga footage, Mildener checked for behaviors that fit these categories. Two of the whales mostly ignored the mirror, which could be due to a variety of factors, including personality or visual acuity, Reiss says. (In many mirror test studies across species who can recognize themselves, some individuals pass while others fail.)

But two belugas appeared very interested: Natasha and her daughter Maris. During their first mirror session, they both clapped their jaws at their own reflections, which belugas sometimes do when they’re trying to intimidate another beluga. Then they began contingency testing. Natasha nodded her head at the mirror, while Maris waggled hers up and down and side to side.

In their second mirror session, both whales moved on to self-directed behaviors. They watched themselves barrel-rolling and looked inside their own mouths. Maris reared up and flapped her pectoral fins at the mirror, in a jazzy move researchers named a "pec shimmy." 

Both frequently approached the mirror, blew bubbles with their mouths or blowholes, and then bit the bubbles. For Mildener, watching this was a treat—as well as proof that something unusual was going on. "Those aren't really behaviors you see when a mirror is not present," he says. "It was just really beautiful to watch." 

They also spent a lot of time simply looking at themselves. Comparing Natasha and Maris's mirror-directed behaviors with how they acted near the clear plexiglass control, it was evident that the two of them had demonstrated mirror self-recognition.

On your mark

Once an individual has cleared this hurdle, researchers often give them what's known as a "mark test." They'll draw a mark on the animal that the animal can't see without a mirror and check whether the animal can use the mirror to find it. 

For Natasha and Maris's mark tests, the researchers drew several marks on either their left or right sides. While Maris didn’t pass any of her mark tests, Natasha spent an unusual amount of time oriented toward her marked side, sometimes pressing it up against the mirror. It was determined that she had passed this test, too, which “further confirm[s] the ability” in this species, Reiss says. 

Since these tests were performed in 2001, scientists have continued to refine this area of research. And the discovery of the cleaner wrasse’s mirror self-recognition in 2023 showed that species don’t necessarily need large brains to demonstrate this trait.

Masanori Kohda, a professor at Osaka Metropolitan University who led the cleaner wrasse research, thinks that any animal who can recognize other individuals of its species can probably also recognize itself. “From this perspective, the present report of [mirror self-recognition] in belugas seems quite expected,” says Kohda. “That said, it is of course still a valuable study.”

Mildener and Reiss now hope to do similar tests with other belugas. It may do more than just increase our scientific understanding. “Finding these shared capabilities and shared levels of consciousness and self-awareness in other species seem to engender more empathy [for them],” Reiss says. For example, research into humpback whale culture and behavior in the 1970s helped lead to landmark conservation legislation, including the Endangered Species Act and the Marine Mammal Protection Act. 

Plus, they say, the animals seem to enjoy the research. "We try to do things that are interesting and fun for them," Reiss says, "but also enrich our scientific awareness."